优点：可以实现java和js之间的调用（适用于只有java和js文件之间的通讯） 其他有webview的没必要使用这种方法
缺点：apk增加将近7MB: 所用到的资源必须手动释放
1：在build.gradle中添加依赖
dependencies {
compile 'com.eclipsesource.j2v8:j2v8:4.5.0@aar'
}
2:必须创建运行环境，用完必须释放
V8 runtime = V8.createV8Runtime();//创建 可放在onCreate()当中
//操作
runtime.release();//释放 可放在onDestroy()当中
3：创建之后，加载写好的js文件，里面包含java可能调用的js方法和一些数据
2：java里面加载js文件的异步任务类：
package com.carnoc.news.j2v8;
import android.app.Activity;
import android.content.Context;
import android.content.res.AssetManager;
import android.graphics.Bitmap;
import android.os.AsyncTask;
import com.amap.api.services.proguard.bf;
import com.carnoc.news.model.HotColumnInfoModel;
import com.carnoc.news.task.AsyncTaskBackListener;
import com.eclipsesource.v8.V8;
import com.eclipsesource.v8.V8Array;
import com.eclipsesource.v8.V8Object;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.List;
/**
* Desc:
* Created by qyn on 2018/4/9.
*/
public class J2V8ReadJavaScript extends AsyncTask<String, String, String>
{
private AsyncTaskBackListener<String> listener;
private String fileName;
private Activity activity;
public J2V8ReadJavaScript(Activity activity, AsyncTaskBackListener<String> listener, String fileName)
{
this.listener = listener;
this.fileName = fileName;
this.activity = activity;
}
public J2V8ReadJavaScript()
{
super();
}
public static String getFileContent(String fileName, Context context)
{
//将json数据变成字符串
StringBuilder stringBuilder = new StringBuilder();
try
{
//获取assets资源管理器
AssetManager assetManager = context.getAssets();
//通过管理器打开文件并读取
BufferedReader bf = new BufferedReader(new InputStreamReader(
assetManager.open(fileName)));
String line;
while ((line = bf.readLine()) != null)
{
stringBuilder.append(line).append("\r\n");//为了保证js的严格“行”属性，这里主动追加\r\n
}
bf.close();
}
catch (IOException e)
{
e.printStackTrace();
}
return stringBuilder.toString();
}
@Override
protected String doInBackground(String... strparams)
{
String jsString = getFileContent(this.fileName, this.activity);
return jsString;
}
@Override
protected void onPostExecute(String result)
{
if (listener != null)
{
listener.onAsyncTaskCallBack(result);
}
}
}
3:java里面初始化数据
J2V8ReadJavaScript readJavaScript = new J2V8ReadJavaScript(mActivity, new AsyncTaskBackListener<String>()
{
@Override
public void onAsyncTaskCallBack(String s)
{
if (v8 != null && !v8.isReleased())
{
registerJavaMethod();
v8.executeScript(s);
///初始化JS数据
V8Array defaultDatas;
defaultDatas = new V8Array(v8);//1:id,2:image,3:color,4:follow,5:platform
defaultDatas.push(2);//2:android
v8.executeVoidFunction("initViewModel", defaultDatas);
defaultDatas.release();
initData();
}
}
}, "JsonHandleJS/quick_news.js");
readJavaScript.execute();
4:java调用js函数处理，这里因为常用的就几种，所以写了一个公共的工具：
package com.carnoc.news.util;
import com.eclipsesource.v8.V8;
import com.eclipsesource.v8.V8Array;
/**
* Desc:
* Created by qyn on 2018/4/17.
*/
public class J2V8Util
{
/**
*
* @param v8
* @param name js函数名
* @return 返回字符串
*/
public static String v8String(V8 v8, String name)
{
String result = "";
if (v8 != null&&!v8.isReleased())
result = v8.executeStringFunction(name, null);
return result;
}
/**
*
* @param v8
* @param name js函数名
* @param position 传入参数
* @return 返回字符串
*/
public static String v8String(V8 v8, String name, int position)
{
String result = "";
if (v8 != null&&!v8.isReleased())
{
V8Array array = new V8Array(v8);
array.push(position);
result = v8.executeStringFunction(name, array);
array.release();
}
return result;
}
/**
*
* @param v8
* @param name js函数名
* @return boolean类型
*/
public static boolean v8Boolean(V8 v8, String name)
{
boolean result = false;
if (v8 != null&&!v8.isReleased())
result = v8.executeBooleanFunction(name, null);
return result;
}
public static boolean v8Boolean(V8 v8, String name, int position)
{
boolean result = false;
if (v8 != null&&!v8.isReleased())
{
V8Array array = new V8Array(v8);
array.push(position);
result = v8.executeBooleanFunction(name, array);
array.release();
}
return result;
}
public static int v8Int(V8 v8, String name, int position)
{
int result = 0;
if (v8 != null&&!v8.isReleased())
{
V8Array array = new V8Array(v8);
array.push(position);
result = v8.executeIntegerFunction(name, array);
array.release();
}
return result;
}
public static int v8Int(V8 v8, String name)
{
int result = 0;
try
{
if (v8 != null&&!v8.isReleased())
result = v8.executeIntegerFunction(name, null);
}
catch (Exception e)
{
}
return result;
}
public static void v8Void(V8 v8, String name, int position)
{
if (v8 != null&&!v8.isReleased())
{
V8Array array = new V8Array(v8);
array.push(position);
v8.executeVoidFunction(name, array);
array.release();
}
return;
}
public static void v8Void(V8 v8, String name)
{
if (v8 != null&&!v8.isReleased())
v8.executeVoidFunction(name, null);
return;
}
}
5:js调用java 这个需要在调用之前 在v8里面注册方法名 例如：
if (v8 != null && !v8.isReleased())
{
//参数1：context 参数2：java方法名，参数三：js里面写的方法名 参数4：方法的参数类型 个数
v8.registerJavaMethod(mContext, "getTitleHeightFromNative", "getTitleHeightFromNative", new Class[]{String.class})
}
public void getTitleHeightFromNative（String str）{
}
