android执行su命令

public boolean () {
    Process process = null;
    DataOutputStream os = null;
    String cmd="chmod 777 " + getPackageCodePath();
    try {
        process = Runtime.getRuntime().exec("su"); 
        os = new DataOutputStream(process.getOutputStream());
        os.writeBytes(cmd + "n");
        os.writeBytes("exitn");
        os.flush();
        process.waitFor();
    } catch (Exception e) {
        return false;
    } finally {
        try {
            if (os != null) {
                os.close();
            }
            process.destroy();
        } catch (Exception e) {
        }
    }
    return true;
}

public String execRootCmd(String cmd) {
    DataInputStream is = null;
    DataOutputStream os = null;
    String content = "";
    try {
        Process process = Runtime.getRuntime().exec("su");
        os = new DataOutputStream(process.getOutputStream());
        is = new DataInputStream(process.getInputStream());
        os.writeBytes(cmd + "nexitn");
        os.flush();
        while (true) {
            String line = is.readLine();
            if (line == null) {
                break;
            }
            content += line + "n";
        }
        //process.waitFor();
        //return process.exitValue();
        return content;
    } catch (Exception e) {
        e.printStackTrace();
    } finally {
        try {
            if (is != null) {
                is.close();
            }
            if (os != null) {
                os.close();
            }
            process.destroy();
        } catch (Exception e) {
        }
    }
    return "";
}