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技术学习

Android

Json Test app

• 进行HttpURLConnection的测试和对获取到的流进行Json解析

4.25

• 从无穷尽的AS崩溃中脱离出来，决心重装

4.26-4.27

• 新建了Json Test 项目并进行测试
• 发现会出现只有此api没有获取到数据，但其他网页或者api可以成功返回数据的bug
• 后面删除并重写(同样的代码)了MainActivity中的代码后终于恢复正常

4.28

• 完成了对JSON的初步解析

源代码

public class MainActivity extends AppCompatActivity implements View.OnClickListener{
    TextView responseText;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Button sendRequest = (Button) findViewById(R.id.mainActivity_btn_sendRequest);
        responseText = (TextView) findViewById(R.id.mainActivity_tv_setUi);
        sendRequest.setOnClickListener(this);
    }
    @Override
    public void onClick(View v) {
        if (v.getId() == R.id.mainActivity_btn_sendRequest) {
           sendRequestWithHttpURLConnection();
        }
    }
    private void sendRequestWithHttpURLConnection() {
        // 开启线程来发起网络请求
        new Thread(new Runnable() {
            @Override
            public void run() {
                HttpURLConnection connection = null;
                BufferedReader reader = null;
                try {
                    URL url = new URL("http://news-at.zhihu.com/api/4/themes");
                    connection = (HttpURLConnection) url.openConnection();
                    connection.setRequestMethod("GET");
                    connection.setConnectTimeout(8000);
                    connection.setReadTimeout(8000);
                    InputStream in = connection.getInputStream();
                    // 下面对获取到的输入流进行读取
                    reader = new BufferedReader(new InputStreamReader(in));
                    StringBuilder response = new StringBuilder();
                    String line;
                    while ((line = reader.readLine()) != null) {
                        response.append(line);
                    }
                    showResponse(response.toString());
                    parseJSONObject(response.toString());
                } catch (Exception e) {
                    e.printStackTrace();
                } finally {
                    if (reader != null) {
                        try {
                            reader.close();
                        } catch (IOException e) {
                            e.printStackTrace();
                        }
                    }
                    if (connection != null) {
                        connection.disconnect();
                    }
                }
            }
        }).start();
    }
    private void showResponse(final String response) {
        runOnUiThread(new Runnable() {
            @Override
            public void run() {
                // 在这里进行UI操作，将结果显示到界面上
                responseText.setText(response);
            }
        });
    }
    private void parseJSONObject(String jsonData) {
        try {
            JSONObject jsonObjectData = new JSONObject(jsonData);
            JSONArray jsonArray = jsonObjectData.getJSONArray("others");
            for (int i = 0; i<jsonArray.length(); i++) {
                JSONObject jsonObject = jsonArray.getJSONObject(i);
                String description = jsonObject.getString("description");
                Log.d("MainActivity",description);
            }
        } catch (JSONException e) {
            e.printStackTrace();
        }
    }
}

测试截图

4.28晚上以及4.29凌晨

• 完成对新闻频道的读取和选择新闻频道显示对应的详情
• 下午和晚上的时候，这个app突然崩溃了，多次log调教+百度+google无解后重新开了一个新项目
• 新项目再一次崩溃，看回原代码后决心在原代码的基础上重写代码
• 原代码拯救成功

源代码

- MainActivity

public class MainActivity extends AppCompatActivity implements View.OnClickListener {
    private TextView responseText;
    private List<NewsChannel> list = new ArrayList<NewsChannel>();
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        responseText = (TextView) findViewById(R.id.mainActivity_tv_setUi);
        Button sendRequest = (Button) findViewById(R.id.btn);
        sendRequest.setOnClickListener(this);
        Button btn = (Button) findViewById(R.id.btn1);
       btn.setOnClickListener(this);
    }
    @Override
    public void onClick(View v) {
        if (v.getId() == R.id.btn) {
            sendRequestWithHttpURLConnection();
        }
        if (v.getId() == R.id.btn1) {
            Intent intent = new Intent(MainActivity.this,SecondActivity.class);
            ArrayList<String> nameList = new ArrayList<>();
            HashMap<String,String> map = new HashMap<String, String>();
            for (NewsChannel channel : list ){
                nameList.add(channel.mName);
                map.put(channel.mName,channel.mDescription);
            }
            ArrayList<HashMap<String,String>> list = new ArrayList<HashMap<String, String>>();
            list.add(0,map);
            intent.putExtra("name", nameList);
            intent.putExtra("map",list);
            startActivity(intent);
        }
    }
    private void sendRequestWithHttpURLConnection() {
        // 开启线程来发起网络请求
        new Thread(new Runnable() {
            @Override
            public void run() {
                HttpURLConnection connection = null;
                BufferedReader reader = null;
                try {
                    URL url = new URL("http://news-at.zhihu.com/api/4/themes");
                    connection = (HttpURLConnection) url.openConnection();
                    connection.setRequestMethod("GET");
                    connection.setConnectTimeout(8000);
                    connection.setReadTimeout(8000);
                    InputStream in = connection.getInputStream();
                    // 下面对获取到的输入流进行读取
                    reader = new BufferedReader(new InputStreamReader(in));
                    StringBuilder response = new StringBuilder();
                    String line;
                    while ((line = reader.readLine()) != null) {
                        response.append(line);
                    }
                    showResponse(response.toString());
                  parseJSONObject(response.toString());
                } catch (Exception e) {
                    e.printStackTrace();
                } finally {
                    if (reader != null) {
                        try {
                            reader.close();
                        } catch (IOException e) {
                            e.printStackTrace();
                        }
                    }
                    if (connection != null) {
                        connection.disconnect();
                    }
                }
            }
        }).start();
    }
    private void showResponse(final String response) {
        runOnUiThread(new Runnable() {
            @Override
            public void run() {
                // 在这里进行UI操作，将结果显示到界面上
                responseText.setText(response);
            }
        });
    }
    private void parseJSONObject(String jsonData) {
        /*
         * others: 新闻类型列表
         thumbnail : 供显示的图片地址
         description : 主题日报的介绍
         id: 新闻类型的唯一表示, 可用于获取该类型下的新闻列表
         name: 新闻类型的名字
         */
        try {
            JSONObject jsonObjectData = new JSONObject(jsonData);
            JSONArray jsonArray = jsonObjectData.getJSONArray("others");
            NewsChannel newsChannel;
            for (int i = 0; i < jsonArray.length(); i++) {
                Parcel parcel = Parcel.obtain();
                newsChannel = new NewsChannel();
                JSONObject jsonObject = jsonArray.getJSONObject(i);
                String description = jsonObject.getString("description");
                String name = jsonObject.getString("name");
                newsChannel.mDescription = description;
                newsChannel.mName = name;
                list.add(newsChannel);
                parcel.recycle();
            }
        } catch (JSONException e) {
            e.printStackTrace();
        }
    }
}

- SecondActivity

public class SecondActivity extends AppCompatActivity {
    private Spinner mSpinnerSelect;
    private SimpleAdapter mSimpleAdapter;
    private List<NewsChannel> mList = new ArrayList<NewsChannel>();
     HashMap<String,String> map;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_second);
        Intent intent = getIntent();
        ArrayList<String> nameList = intent.getStringArrayListExtra("name");
        ArrayList<HashMap<String,String>> list = (ArrayList<HashMap<String, String>>) intent.getSerializableExtra("map");
         map = list.get(0);
        ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_item, nameList);
        adapter.setDropDownViewResource(android.R.layout.simple_list_item_single_choice);
        Spinner sp = (Spinner) findViewById(R.id.spinner);
        sp.setAdapter(adapter);
        sp.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
            // parent： 为控件Spinner view：显示文字的TextView position：下拉选项的位置从0开始
            public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
                TextView tvResult = (TextView) findViewById(R.id.tvResult);
//获取Spinner控件的适配器
                ArrayAdapter<String> adapter = (ArrayAdapter<String>) parent.getAdapter();
                tvResult.setText(map.get(adapter.getItem(position)));
            }
            //没有选中时的处理
            public void onNothingSelected(AdapterView<?> parent) {
            }
        });
    }
}

测试截图

- MainActivity

- SecondActivity

• 截图1
  

• 截图2