[移动开发]安卓WebView文件上传的实现（解决安卓WebView中＜input type=‘file‘/＞标签点击没反应）

网页端上传文件常用<input type='file'/>标签，放上这个标签，浏览器就会出现这个文件选择器，点击就可以弹出文件选择窗口，很是简单方便，不过，包含<input type='file'/>标签的网页要是在安卓WebView中渲染，<input type='file'/>这个标签就会失效，用户点击后毫无反应，根本原因就是安卓WebView没有实现具体的文件选择器方法，对应的方法是空的，我们要安卓WebView支持<input type='file'/>只能重写对应的方法，调用原生java代码去实现文件上传的功能，大体可以分为以下几步：

1、重载文件选择按钮被点击后的方法，即onShowFileChooser()方法。

2、在onShowFileChooser()方法中声明一个意图，打开文件选择相对应的Activity，即FILE_CHOOSER_RESULT_CODE。

3、重载onActivityResult()方法，在里面接收用户选择的文件的Uri，传给input标签

下面还是直接上代码：

package com.test.sdxjwkq;

import androidx.appcompat.app.AppCompatActivity;
import android.annotation.TargetApi;
import android.app.Activity;
import android.content.ClipData;
import android.os.Build;
import android.os.Bundle;
import android.webkit.WebView;
import android.webkit.WebChromeClient;
import android.net.Uri;
import android.webkit.ValueCallback;
import android.content.Intent;
import android.text.TextUtils;
import android.webkit.WebViewClient;
import android.os.Environment;

public class MainActivity extends AppCompatActivity {
    private ValueCallback<Uri> uploadMessage;
    private ValueCallback<Uri[]> uploadMessageAboveL;
    private final static int FILE_CHOOSER_RESULT_CODE = 10000;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        webView=findViewById(R.id.webView1);
        webView.getSettings().setJavaScriptEnabled(true);//支持javascript
        webView.getSettings().setAllowContentAccess(true);
        webView.getSettings().setAllowFileAccess(true);
        // 开启DOM缓存，开启LocalStorage存储（html5的本地存储方式）
        webView.getSettings().setDomStorageEnabled(true);
        webView.getSettings().setDatabaseEnabled(true);
        webView.getSettings().setDatabasePath(MainActivity.this.getApplicationContext().getCacheDir().getAbsolutePath());
        //javascript接口映射
        //webView.addJavascriptInterface(new Utils(), "Utils");
        //webView.addJavascriptInterface(new Sql(), "Sql");
        webView.setWebChromeClient(new WebChromeClient() {
            // For Android >= 5.0
            @Override
            public boolean onShowFileChooser(WebView webView, ValueCallback<Uri[]> filePathCallback, WebChromeClient.FileChooserParams fileChooserParams) {
                uploadMessageAboveL = filePathCallback;
                openImageChooserActivity();
                return true;
            }
        });

        webView.loadUrl("file:///android_asset/main.html");
        //webView.loadUrl("file:///"+Environment.getExternalStorageDirectory()+"/Enen/main.html");
    }
    private void openImageChooserActivity() {
        Intent i = new Intent(Intent.ACTION_GET_CONTENT);
        i.addCategory(Intent.CATEGORY_OPENABLE);
        i.setType("image/*");
        startActivityForResult(Intent.createChooser(i, "Image Chooser"), FILE_CHOOSER_RESULT_CODE);
    }
    private static WebView webView;
    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        if (requestCode == FILE_CHOOSER_RESULT_CODE) {
            if (null == uploadMessage && null == uploadMessageAboveL) return;
            Uri result = data == null || resultCode != RESULT_OK ? null : data.getData();
            if (uploadMessageAboveL != null) {
                onActivityResultAboveL(requestCode, resultCode, data);
            } else if (uploadMessage != null) {
                uploadMessage.onReceiveValue(result);
                uploadMessage = null;
            }
        }
    }

    @TargetApi(Build.VERSION_CODES.LOLLIPOP)
    private void onActivityResultAboveL(int requestCode, int resultCode, Intent intent) {
        if (requestCode != FILE_CHOOSER_RESULT_CODE || uploadMessageAboveL == null)
            return;
        Uri[] results = null;
        if (resultCode == Activity.RESULT_OK) {
            if (intent != null) {
                String dataString = intent.getDataString();
                ClipData clipData = intent.getClipData();
                if (clipData != null) {
                    results = new Uri[clipData.getItemCount()];
                    for (int i = 0; i < clipData.getItemCount(); i++) {
                        ClipData.Item item = clipData.getItemAt(i);
                        results[i] = item.getUri();
                    }
                }
                if (dataString != null)
                    results = new Uri[]{Uri.parse(dataString)};
            }
        }
        uploadMessageAboveL.onReceiveValue(results);
        uploadMessageAboveL = null;
    }

}