android选择文件（安卓系统文件夹详解）

废话没有，先看效果

第一步：创建mainactivity

import android.app.activity;
import android.content.context;
import android.content.intent;
import android.os.bundle;
import android.view.view;
import android.widget.button;
import android.widget.textview;

import com.rdsa.singleselectedfileorfolder.r;

import java.util.arraylist;

public class mainactivity extends appcompatactivity {

    public context mcontext;
    private button selectfile, selectfolder, mselectfile, mselectfolder;
    private textview result;
    private activity activity;

    @override
    protected void oncreate(bundle savedinstancestate) {
        super.oncreate(savedinstancestate);
        this.mcontext = this;
        this.activity = this;
        setcontentview(r.layout.activity_main);

        initview();
        initdata();
        initevent();
    }

    @override
    protected void onactivityresult(int requestcode, int resultcode, intent data) {
        super.onactivityresult(requestcode, resultcode, data);

        if (requestcode == choosefileordiractivity.requestcode && resultcode == choosefileordiractivity.resultcode) {
            arraylist<string> respath = data.getstringarraylistextra(choosefileordiractivity.resultdata);
            stringbuffer sb = new stringbuffer();
            for(string item : respath) {
                sb.append(item).append("rn");
            }
            result.settext(sb.tostring());
        }
    }

    private void initview() {
        this.result = super.findviewbyid(r.id.result);
        this.selectfile = super.findviewbyid(r.id.selectfile);
        this.selectfolder = super.findviewbyid(r.id.selectfolder);
        this.mselectfile = super.findviewbyid(r.id.mselectfile);
        this.mselectfolder = super.findviewbyid(r.id.mselectfolder);
    }

    private void initdata() {

    }

    private void initevent() {
        selectfile.setonclicklistener(new view.onclicklistener() {
            @override
            public void onclick(view view) {
                intent intent = new intent(activity, choosefileordiractivity.class);
                intent.putextra(choosefileordiractivity.entervar, choosefileordiractivity.singlefile);
                activity.startactivityforresult(intent, choosefileordiractivity.requestcode);
            }
        });

        selectfolder.setonclicklistener(new view.onclicklistener() {
            @override
            public void onclick(view view) {
                intent intent = new intent(activity, choosefileordiractivity.class);
                intent.putextra(choosefileordiractivity.entervar, choosefileordiractivity.singlefolder);
                activity.startactivityforresult(intent, choosefileordiractivity.requestcode);
            }
        });

        mselectfile.setonclicklistener(new view.onclicklistener() {
            @override
            public void onclick(view view) {
                intent intent = new intent(activity, choosefileordiractivity.class);
                intent.putextra(choosefileordiractivity.entervar, choosefileordiractivity.multifile);
                activity.startactivityforresult(intent, choosefileordiractivity.requestcode);
            }
        });

        mselectfolder.setonclicklistener(new view.onclicklistener() {
            @override
            public void onclick(view view) {
                intent intent = new intent(activity, choosefileordiractivity.class);
                intent.putextra(choosefileordiractivity.entervar, choosefileordiractivity.multifolder);
                activity.startactivityforresult(intent, choosefileordiractivity.requestcode);
            }
        });
    }
}

第二步：创建mainactivity布局文件activity_main.xml

<linearlayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context="com.rdsa.selectedfileorfolder.mainactivity">


    <button
        android:id="@+id/selectfolder"
        android:text="文件夹选择(单选)"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"   />

    <button
        android:id="@+id/selectfile"
        android:text="文件选择（单选）"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"   />

    <button
        android:id="@+id/mselectfolder"
        android:text="文件夹选择(多选)"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"   />

    <button
        android:id="@+id/mselectfile"
        android:text="文件选择（多选）"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"   />

    <textview
        android:id="@+id/result"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="wait for result" />


</linearlayout>

第三步：创建目录数据存储类fileordirbeans

public class fileordirbeans {
    string isfile, name, ischeckvisible, ischecked, absolutepath ;

    public fileordirbeans(string... params) {
        this.isfile = params[0];
        this.name = params[1];
        this.ischeckvisible = params[2];
        this.ischecked = params[3];
        this.absolutepath = params[4];
    }

    public string getisfile() {
        return isfile;
    }

    public void setisfile(string isfile) {
        this.isfile = isfile;
    }

    public string getname() {
        return name;
    }

    public void setname(string name) {
        this.name = name;
    }

    public string getischeckvisible() {
        return ischeckvisible;
    }

    public void setischeckvisible(string ischeckvisible) {
        this.ischeckvisible = ischeckvisible;
    }

    public string getischecked() {
        return ischecked;
    }

    public void setischecked(string ischecked) {
        this.ischecked = ischecked;
    }

    public string getabsolutepath() {
        return absolutepath;
    }

    public void setabsolutepath(string absolutepath) {
        this.absolutepath = absolutepath;
    }
}

第四步：创建文件浏览choosefileordiractivity

import android.manifest;
import android.app.activity;
import android.content.intent;
import android.content.pm.packagemanager;
import android.os.build;
import android.os.bundle;
import android.os.environment;
import android.view.keyevent;
import android.view.view;
import android.widget.button;
import android.widget.listview;
import android.widget.textview;

import com.rdsa.singleselectedfileorfolder.r;
import java.io.file;
import java.util.arraylist;
import java.util.arrays;
import java.util.collections;
import java.util.comparator;
import java.util.list;

public class choosefileordiractivity extends activity {
    public static final string entervar = "entervar";
    public static final string resultdata = "selected";
    public static final int requestcode = 888;
    public static final int resultcode = 999;
    public static final int singlefile = 1000;
    public static final int singlefolder = 2000;
    public static final int multifile = 3000;
    public static final int multifolder = 2001;


    private string rootpath = environment.getexternalstoragedirectory().getabsolutepath();

    private static final int requescode = 5;
    private static final string need_permission = manifest.permission.write_external_storage;
    private listview listview4file;
    private textview nodatatip;
    private button btchose;
    private list<string> data;
    private arraylist<fileordirbeans> fileordirlist;
    private fileadapter fileadapter;



    private int entervar;

    @override
    protected void oncreate(bundle savedinstancestate) {
        super.oncreate(savedinstancestate);
        setcontentview(r.layout.ly_choose_file_or_folder);

        this.entervar = this.getintent().getintextra(entervar, singlefile);

        this.initview();
        this.initdata();
        this.initevent();

    }

    private void initdata() {
        this.listview4file.setemptyview(nodatatip);

        this.data = new arraylist<>();
        this.fileordirlist = new arraylist<>();
        this.fileadapter = new fileadapter(this, fileordirlist, entervar);
        this.listview4file.setadapter(fileadapter);

        if (build.version.sdk_int >= 23) {      // 判断系统版本是否大于6.0
            if (checkselfpermission(need_permission) == packagemanager.permission_granted) {  //检查是否有读写权限
                loaddatafrompath(rootpath, entervar);//从路径中加载数据
            } else {
                requestpermissions(new string[]{need_permission}, requescode); // 申请权限
            }
        } else {
            loaddatafrompath(rootpath, entervar);//系统版本小于6.0直接加载数据
        }
    }

    private void loaddatafrompath(final string mpath, final int type) {
        this.data.clear();    // data为 listview 中要显示的数据
        this.fileordirlist.clear();

        new thread() {
            public void run() {
                super.run();

                data = orderbyname(mpath, type == singlefolder || type == multifolder);
                fileordirlist = getbeans(data, type);

                runonuithread(new runnable() {
                    @override
                    public void run() {
                        fileadapter.setdata(data, fileordirlist);//将数据载入适配器当中
                    }
                });
            }
        }.start();
    }

    private arraylist<fileordirbeans> getbeans(list<string> filelist, final int type) {
        arraylist<fileordirbeans> resultlist = new arraylist<>();
        for(string fileitem : filelist) {
            file file = new file(fileitem);

            string isfile = string.valueof(file.isfile());
            string ischeckvisible = (file.isfile() || type == singlefolder || type == multifolder) ?  "true" : "false";;

            fileordirbeans bean = new fileordirbeans(isfile, file.getname(), ischeckvisible, "false", fileitem);
            resultlist.add(bean);
        }
        return resultlist;
    }

    private void initview() {
        listview4file = findviewbyid(r.id.rvfileview);
        nodatatip = findviewbyid(r.id.nodatatip);
    }

    private void initevent() {

        fileadapter.setevent(new fileadapter.event() {
            @override
            public void enternextdir(string path) {
                rootpath = path;
                loaddatafrompath(rootpath, entervar);
            }
        });

        findviewbyid(r.id.btchose).setonclicklistener(new view.onclicklistener() {
            @override
            public void onclick(view view) {
                intent intent = new intent();
                intent.putstringarraylistextra(resultdata, fileadapter.getselectdata());
                setresult(resultcode, intent);
                finish();
            }
        });
    }

    @override
    public void onrequestpermissionsresult(int requestcode, string[] permissions, int[] grantresults) {
        super.onrequestpermissionsresult(requestcode, permissions, grantresults);
        if (requestcode == requescode && permissions[0].equals(need_permission)) {
            loaddatafrompath(rootpath, entervar);
        }
    }

    @override
    public boolean onkeydown(int keycode, keyevent event) {
        if (event.getkeycode() == keyevent.keycode_back) {//点击的是返回键
            if (event.getaction() == keyevent.action_down && event.getrepeatcount() == 0) {//按键的按下事件
                if (rootpath.trim().equals(environment.getexternalstoragedirectory().getabsolutepath())) {
                    return super.onkeydown(keycode, event);
                } else {
                    file file = new file(rootpath);
                    if (!file.exists()) {
                        return super.onkeydown(keycode, event);
                    }
                    rootpath = file.getparent();
                    loaddatafrompath(rootpath, entervar);
                    return false;
                }
            }
        }
        return super.onkeydown(keycode, event);
    }


    public static arraylist<string> orderbyname(string filepath, boolean excludefile) {
        arraylist<string> filenamelist = new arraylist<string>();
        file file = new file(filepath);
        file[] files = file.listfiles();
        list filelist = arrays.aslist(files);
        collections.sort(filelist, new comparator<file>() {
            @override
            public int compare(file o1, file o2) {
                if (o1.isdirectory() && o2.isfile())
                    return -1;
                if (o1.isfile() && o2.isdirectory())
                    return 1;
                return o1.getname().compareto(o2.getname());
            }
        });
        for (file itemfile : files) {
            if(itemfile.getname().startswith(".")) {
                continue;
            } else {
                if(itemfile.isfile() && excludefile) {
                    continue;
                }
                filenamelist.add(itemfile.getabsolutepath());  //往集合中添加符合条件的数据
            }
        }
        return filenamelist;
    }
}

第五步：创建choosefileordiractivity布局文件
ly_choose_file_or_folder.xml

<?xml version="1.0" encoding="utf-8"?>
<linearlayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <relativelayout
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:background="#f9f9fa">

        <textview
            android:id="@+id/tvtitle"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_centerinparent="true" />

        <button
            android:id="@+id/btchose"
            android:layout_width="wrap_content"
            android:layout_height="30dp"
            android:layout_alignparentright="true"
            android:layout_centervertical="true"
            android:layout_marginright="5dp"
            android:background="@drawable/bg_button"
            android:text="确定"
            android:textcolor="#458b74" />
    </relativelayout>

    <listview
        android:id="@+id/rvfileview"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

    <textview
        android:id="@+id/nodatatip"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="center_vertical|center_horizontal"
        android:text="没有数据可用，返回上一层" />


</linearlayout>

第六步：创建listview的数据容器类fileadapter

import android.content.context;
import android.view.layoutinflater;
import android.view.view;
import android.view.viewgroup;
import android.widget.baseadapter;
import android.widget.checkbox;
import android.widget.compoundbutton;
import android.widget.imageview;
import android.widget.textview;
import com.rdsa.singleselectedfileorfolder.r;
import java.util.arraylist;
import java.util.list;

public class fileadapter extends baseadapter {
    private context context;
    private event event;
    private arraylist<string> selectdata;
    private arraylist<fileordirbeans> fileordirlist;
    private layoutinflater mlayoutinflater;      //   将 item 的 xml 转换成 view
    private final int entervar;

    public fileadapter(context context, final arraylist<fileordirbeans> fileordirlist, int entervar) {
        this.context = context;
        this.selectdata = new arraylist<>();
        this.mlayoutinflater = layoutinflater.from(context);     // context 必须是界面所在的 context

        this.entervar = entervar;
        this.fileordirlist = fileordirlist;
    }

    @override
    public int getcount() {
        return this.fileordirlist.size();
    }

    @override     // 数据项
    public object getitem(int position) {
        return fileordirlist.get(position);
    }

    @override
    public long getitemid(int position) {
        return position;
    }

    @override    // 显示的内容
    public view getview(final int position, view convertview, viewgroup viewgroup) {
        viewholder viewholder;

        if(convertview == null) {
            convertview = mlayoutinflater.inflate(r.layout.filechoose_layout_fileitme, null);
            viewholder = new viewholder();
            viewholder.icon = convertview.findviewbyid(r.id.icon);
            viewholder.filename = convertview.findviewbyid(r.id.filename);
            viewholder.checkbox = convertview.findviewbyid(r.id.checkbox);
            convertview.settag(viewholder);
        } else {
            viewholder = (viewholder)convertview.gettag();
        }

        final fileordirbeans bean = fileordirlist.get(position);
        final string abspath = bean.getabsolutepath();

        bean.setischecked("false");    //   初始化一个boolean值 来判断是否被选中
        for (string s : selectdata) {    // 遍历选中的集合
            if (s.trim().equals(abspath)) {    // 如果集合中的子元素与适配其中的路径相同
                bean.setischecked("true");     // 判断已被选中
                break; //终止循环
            }
        }

        viewholder.checkbox.setoncheckedchangelistener(new compoundbutton.oncheckedchangelistener() {
            @override
            public void oncheckedchanged(compoundbutton compoundbutton, boolean ischecked) {//设置checkbox的点击事件
                if (ischecked) {//选中状态
                    if (selectdata.contains(abspath)) {//如果集合中包含了该元素则直接返回
                        if (entervar == choosefileordiractivity.singlefile || entervar == choosefileordiractivity.singlefolder) {
                            selectdata.clear();
                            selectdata.add(abspath);
                        }
                    } else {//否则添加
                        if(entervar == choosefileordiractivity.singlefile || entervar == choosefileordiractivity.singlefolder) {
                            selectdata.clear();
                        }
                        selectdata.add(abspath);
                    }
                } else {//未选中状态
                    if (selectdata.contains(abspath)) {//如果集合中包含了该元素则移除
                        selectdata.remove(abspath);
                    } else {//否则 返回
                        return;
                    }
                }

                notifydatasetchanged();
            }
        });


        viewholder.icon.setimagedrawable(boolean.parseboolean(bean.getisfile()) ?  context.getresources().getdrawable(r.drawable._16_file) : context.getresources().getdrawable(r.drawable._16_folder));
        viewholder.filename.settext(bean.getname());
        viewholder.checkbox.setvisibility((boolean.parseboolean(bean.ischeckvisible))?  view.visible : view.gone);
        viewholder.checkbox.setchecked(boolean.parseboolean(bean.getischecked()));

        viewholder.filename.setonclicklistener(new view.onclicklistener() {
            @override
            public void onclick(view view) {
                if(!boolean.parseboolean(bean.getisfile())) {
                    event.enternextdir(fileordirlist.get(position).getabsolutepath());
                }
            }
        });

        return convertview;
    }

    static class viewholder {
        private imageview icon;
        private textview filename;
        private checkbox checkbox;
    }

    public interface event {
        void enternextdir(string path);//进入下一个文件夹
    }

    public void setdata(list<string> data, arraylist<fileordirbeans> fileordirlist) {
        this.fileordirlist.clear();
        this.fileordirlist.addall(fileordirlist);

        notifydatasetchanged();
    }

    public void setevent(event event) {
        this.event = event;
    }

    public arraylist<string> getselectdata() {
        return selectdata;
    }

}

第七步：创建fileadapter每一项的布局文件
filechoose_layout_fileitme.xml

<?xml version="1.0" encoding="utf-8"?>
<relativelayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="horizontal" >


    <imageview
        android:id="@+id/icon"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginstart="8dp"
        android:layout_marginend="8dp"
        android:layout_alignparentstart="true"
        android:layout_centervertical="true"
        android:src="@drawable/file" />

    <textview
        android:id="@+id/filename"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginbottom="8dp"
        android:layout_margintop="8dp"
        android:paddingright="50dp"
        android:layout_torightof="@+id/icon"
        android:layout_centervertical="true"
        android:text="textview"  />

    <checkbox
        android:id="@+id/checkbox"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignparentend="true"
        android:layout_centervertical="true"
        android:layout_marginend="8dp" />

</relativelayout>

第八步：androidmanifest 增加对文件操作的授权

<uses-permission android:name="android.permission.read_external_storage" />
<uses-permission android:name="android.permission.write_external_storage" />

第九步：用到的图片资源_16_file.png和_16_folder.png