超简单实现Android 屏幕截屏（需要系统级权限）

1.思路 通过cmd 命令 :adb shell screencap -p /sdcard/screen.png 来实现

2.添加系统签名及权限
 

    android:sharedUserId="android.uid.system"

    
    
    

3.创建 命令工具类：CmdUtil

import android.support.annotation.NonNull;
import android.text.TextUtils;
import android.util.Log;

import java.io.BufferedReader;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;

public class CmdUtil {
    private static final String TAG = "CmdUtil";

    private static final String COMMAND_SH = "sh";
    private static final String COMMAND_EXIT = "exit\n";
    private static final String COMMAND_LINE_END = "\n";


    /**
     * 运行命令
     *
     * @param command 命令
     * @return 结果
     */
    public static Result execute(String command) {
        Log.i(TAG, "execute() command = " + command);
        Result result = new Result();

        if (TextUtils.isEmpty(command)) {
            Log.w(TAG, "WARNING: command should not be null or empty");
            return result;
        }

        Process process = null;
        DataOutputStream dos = null;

        try {
            process = Runtime.getRuntime().exec(COMMAND_SH);
            dos = new DataOutputStream(process.getOutputStream());
            dos.write(command.trim().getBytes());
            dos.writeBytes(COMMAND_LINE_END);
            dos.flush();
            dos.writeBytes(COMMAND_EXIT);
            dos.flush();
            result.code = process.waitFor();
            result.success = readBuffer(new BufferedReader(new InputStreamReader(process.getInputStream())));
            result.error = readBuffer(new BufferedReader(new InputStreamReader(process.getErrorStream())));
            Log.i(TAG, "result = " + result);
        } catch (IOException ioe) {
            ioe.printStackTrace();
            Log.e(TAG, ioe.getMessage());
        } catch (InterruptedException ie) {
            ie.printStackTrace();
            Log.e(TAG, ie.getMessage());
        } finally {
            try {
                if (null != dos) {
                    dos.close();
                }
            } catch (IOException ioe) {
                ioe.printStackTrace();
                Log.e(TAG, ioe.getMessage());
            }
            if (null != process) {
                process.destroy();
            }
        }
        return result;
    }

    @NonNull
    private static String readBuffer(BufferedReader bufferedReader) throws IOException {
        StringBuilder sb = new StringBuilder();
        String s;
        while ((s = bufferedReader.readLine()) != null) {
            sb.append(s);
        }
        return sb.toString();
    }


    /**
     * Command执行结果
     */
    public static final class Result {

        public static final int SUCCESS = 0;
        public static final int ERROR = -1;

        public int code = ERROR;
        String error;
        String success;

        @Override
        public String toString() {
            return "Result{" +
                "code=" + code +
                ", error='" + error + '\'' +
                ", success='" + success + '\'' +
                '}';
        }
    }
}

 4.简单实现

 CmdUtil.execute(" screencap -p /data/screen1.png");

5.导出查看即可（或者指定其他路径）

adb pull /data/screen1.png ./

另附上两个很好的截屏demo：
参考Google官方给的demo以及其他开发者写的Demo

https://github.com/googlesamples/android-ScreenCapture
https://github.com/VincentWYJ/CaptureScreen