Question

嘿有男人和女孩，iv一直试图解决这个问题已经好几周了，而且似乎得到了任何帮助，我希望代码从我的服务器下载一个JSON文件并用saveJSON将其保存到内部存储器中）然后使用showJSON（）它应该显示保存的JSON文件，然后将其解码为纯文本。我得到的问题是围绕HttpResponse和下一行，我也不确定它的下一部分也写在应该保存JSON文件的地方。这是我得到的两个错误

Error in http connection java.net.SocketException: Permission denied

和

Error saving string null.pointer

任何帮助将不胜感激

    public class MainActivity extends Activity {

String storyObj = "";
Object json = null;
HttpEntity entity = null;
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);


    //button that saves the file from mySQL
    Button save = (Button) findViewById(R.id.downloadBtn);
    save.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {
            saveJson();             
        }
    });

    //Button that opens the file from InternalMemory
    Button open = (Button) findViewById(R.id.showBtn);
    open.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {
            openJson();             
        }
    });


//end of onCreate() 
}


//saveJson pull a JSON file from mySQl server then saves that file in its JSON type eg .json
public void saveJson(){
    TextView test = (TextView) findViewById(R.id.showView);


    try{
        //connects to mySQL
        HttpClient client = new DefaultHttpClient();
        HttpPost post = new HttpPost("http://10.0.2.2/textures_story_list.php");
        HttpResponse response = client.execute(post);
        //captures the response
        entity = response.getEntity();

    }catch(Exception e) {
         Log.e("log_tag", "Error in http connection "+e.toString());
    }
    try{
        Object json = entity;
        String FILENAME = "story.json";
        //gives file name
        FileOutputStream output = openFileOutput(FILENAME, MODE_WORLD_READABLE);
        //creates new StreamWriter
        OutputStreamWriter writer = new OutputStreamWriter(output);
        //writes json with file name story.json
        writer.write((Integer) json);
        writer.flush();
        //closes writer
        writer.close();

    }catch(Exception e) {
         Log.e("log_tag", "Error saving string "+e.toString());
    }

//end of saveJson()
}

private char[] Object(Object json2) {
    // TODO Auto-generated method stub
    return null;
}


public void openJson(){
    TextView test = (TextView) findViewById(R.id.showView);



    try{
        FileInputStream fileInput = openFileInput("story.json");

        BufferedReader inputReader = new BufferedReader(new InputStreamReader(fileInput, "UTF-8"), 8);
        StringBuilder strBuilder = new StringBuilder();
            String line = null;
            while ((line = inputReader.readLine()) != null) {
                strBuilder.append(line + "\n");
            }
            fileInput.close();
            storyObj = strBuilder.toString();

    }catch(IOException e){
         Log.e("log_tag", "Error building string "+e.toString());
    }

    try{
        JSONArray jArray = new JSONArray(storyObj);
        String storyNames = "";
        for(int i = 0;i<jArray.length();i++){
            storyNames += jArray.getJSONObject(i).getString("story_name") +"\n";
        }
        test.setText(storyNames);

    }catch(JSONException e) {
         Log.e("log_tag", "Error returning string "+e.toString());
    }
    return;
//and of openJson() 
}




//end of class body    
}

这是我的xml清单

    <?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.game"
android:versionCode="1"
android:versionName="1.0" >

<uses-sdk android:minSdkVersion="8" />

<users-permission
    android:name="android.permission.INTERNET"  />
<users-permission   android:name="android.permission.SET_DEBUG_APP" />

<application
    android:icon="@drawable/ic_launcher"
    android:label="@string/app_name" 
     android:debuggable="true">

    <activity
        android:name=".MainActivity"
        android:label="@string/app_name" >
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>

</application>

</manifest>

Answer 1

如果这确实是您的清单文件，则错误很明显。标记不应该是use[r]s-permission，而是uses-permission：

<uses-permission
    android:name="android.permission.INTERNET"  />
<uses-permission   android:name="android.permission.SET_DEBUG_APP" />

现在您无法访问互联网，从而导致错误。如果您切换到使用像Eclipse这样的IDE并使用自动完成功能，您将从一开始就避免此类错误，但IDE还会将此错误强调为警告。

编辑：关于你得到的错误 - 你试图将响应的实体直接转换为整数。这总是会失败，因为Integer不是HttpEntity的超类。您需要在String中读取实体的内容，然后将字符串的内容解析为整数：

InputStream entityStream = entity.getcontent();
StringBuilder entityStringBuilder = new StringBuilder();
byte [] buffer = new byte[1024];
int bytesReadCount;
while ((bytesReadCount = entityStream.read(buffer)) > 0) {
    entityStringBuilder.append(new String(buffer, 0, bytesReadCount));
}
String entityString = entityStringBuilder.toString();
Integer responseInteger = Integer.valueOf(entityString);

这不是高度优化，而是完成工作。从那时起，您可以根据需要使用responseInteger值。但是，如果您想writer.write，则需要String值，而不是Integer。因此，我建议您使用entityString。

Answer 2

您插入了错误的权限。它必须是这样的

<manifest xlmns:android...>
 ...
 <uses-permission android:name="android.permission.INTERNET"></uses-permission>
</manifest>

您使用过：

<users-permission ...

你在哪里得到String nullpointer？

试图从mySQL下载JSON

2 个答案: