我需要通过程序下载.apk文件，然后启动其活动。 我使用的代码如下Android下载的.apk文件损坏

private String downloadFile(String sourceURL, String destinationPath)

{

try {

URL url = new URL(sourceURL);

URLConnection connection = url.openConnection();

connection.connect();

// download the file

InputStream input = new BufferedInputStream(url.openStream());

OutputStream output = new FileOutputStream(destinationPath);

byte data[] = new byte[1024];

int count;

while ((count = input.read(data)) > 0) {

output.write(data, 0, count);

}

output.flush();

output.close();

input.close();

//此编辑：使文件RW，否则apk文件将不被安装 调用Runtime.getRuntime()EXEC( “搭配chmod 666” +的DestinationPath) ;

message = "OK";

}

catch (MalformedURLException e) {