网络请求

Http的常用请求方式有：

image.png

Get&Post:
网络请求中我们常用键值对来传输参数。

JSON

JSON（JavaScript Object Notation）是一种基于文本的数据交换格式。无论你的应用是用哪种开发语言编写的（Java/EE，Ruby，PHP，C#/.Net等等），你都可以使用JSON来通过网络进行数据交互和处理。
JSON是一种简单数据格式，它有三种数据结构：

• 键值对 —— Name/Value (Key/Value)
• 对象 —— Object
• 数组 —— Arrays

用Android原生技术解析JSON：
1、解析JSON对象的API：JsonObject
JSONObject(String json)；将Json字符串解析成Json对象；
XxxgetXxx(String name) ；根据name在json对象中得到相应的value。

//获取JSON数据
final String content = response.body().string();
JSONObject jsonObject = null;
try {
    //解析JSON对象
    jsonObject = new JSONObject(content);
    JSONObject result = jsonObject.optJSONObject("result");
    final int detailid = result.optInt("detailid");
    final String title = result.optString("title");
    final String type = result.optString("type");
    String c = result.optString("content");
    // 封装Java对象
    detailModel = new DetailModel(detailid, title, type, c);
    System.out.println(detailModel);
    handler.post(new Runnable() {
        @Override
        public void run() {
            Log.d("PoetryTag", "detailid:" + detailid + ", title:" + title + ", type:" + type + ", content:" + content);
            //显示解析后的数据
            tv_title.setText(detailModel.getTitle());
            tv_type.setText(detailModel.getType());
            tv_content.setText(Html.fromHtml(detailModel.getContent()));
        }
    });
} catch (JSONException e) {
    e.printStackTrace();
}

2、解析Json数组的API：JSONArray
JSONArray(String json)；将json字符串解析成json数组；
int length()；得到json数组中元素的个数；
XxxgetXxx(int s) ；根据下标得到json数组中对应的元素数据。

private List<PoetryModel> data(String content) {
    List<PoetryModel> poetryModels = new ArrayList<>();
    try {
        //解析json数组
        JSONObject jsonObject = new JSONObject(content);
        JSONArray jsonArray = jsonObject.optJSONArray("result");

        for (int i = 0; i < jsonArray.length(); i++) {
            JSONObject object = jsonArray.getJSONObject(i);
            if (object != null) {
                int detailid = object.optInt("detailid");
                String name = object.optString("name");
                String author = object.optString("author");
                // 封装Java对象
                PoetryModel poetryModel = new PoetryModel(detailid, name, author);
                //显示解析后的数据
                poetryModels.add(poetryModel);
                Log.d("PoetryTag", "detail:" + detailid + ", name:" + name + ", author:" + author);
            }
        }
    } catch (JSONException e) {
        e.printStackTrace();
    }
    return poetryModels;
}

OkHttp

导入Jar包

implementation 'com.squareup.okhttp3:okhttp:3.2.0’

在日常开发中最常用到的网络请求就是GET和POST两种请求方式。

• Requests（请求）
  每一个HTTP请求中都应该包含一个URL，一个GET或POST方法以及Header或其他参数，当然还可以含特定内容类型的数据流。
• Responses（响应）
  响应则包含一个回复代码（200代表成功，404代表未找到），Header和定制可选的body。

final OkHttpClient client = new OkHttpClient();

public void run(int id) {

    Request request = new Request.Builder()

            .url("[https://api.jisuapi.com/tangshi/detail?appkey=ccb0bd990f91c687&detailid=](https://api.jisuapi.com/tangshi/detail?appkey=ccb0bd990f91c687&detailid=)" + id)

            .get()

            .build();

    client.newCall(request).enqueue(new Callback() {

        @Override

        public void onFailure(Call call, IOException e) {

            e.printStackTrace();

        }

        @Override

        public void onResponse(Call call, Response response) throws IOException {

            if (!response.isSuccessful()) throw new IOException("Unexpected code " + response);

        // ...JSON解析... 

}

• 同步&异步
  这2个概念仅存在于多线程编程中。
  android中默认只有一个主线程，也叫UI线程。因为View绘制只能在这个线程内进行。
  所以如果你阻塞了(某些操作使这个线程在此处运行了N秒)这个线程，这期间View绘制将不能进行，UI就会卡。所以要极力避免在UI线程进行耗时操作。
  网络请求是一个典型耗时操作。
  同步：直接耗时操作阻塞线程直到数据接收完毕然后返回。Android不允许的。
  异步：在子线程进行耗时操作，完成后通过Handler将更新UI的操作发送到主线程执行。

使用handler中的post方法：

handler.post(new Runnable() {
    @Override
    public void run() {
        Log.d("PoetryTag", "detailid:" + detailid + ", title:" + title + ", type:" + type + ", content:" + content);
        //显示解析后的数据
        tv_title.setText(detailModel.getTitle());
        tv_type.setText(detailModel.getType());
        tv_content.setText(Html.fromHtml(detailModel.getContent()));
    }
});

这样处理的话我们就可以不用重写handlerMessage()方法了，适合子线程与主线程进行较为单一的交流。

实例：

MainActivity:

public class MainActivity extends AppCompatActivity implements View.OnClickListener {

    private Button bt_get;
    private Button bt_post;
    private PoetryAdapter adapter;
    private RecyclerView recycler;

    final OkHttpClient client = new OkHttpClient();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        recycler = findViewById(R.id.recycler);
        recycler.setLayoutManager(new LinearLayoutManager(this, RecyclerView.VERTICAL, false));

        bt_get = findViewById(R.id.bt_get);
        bt_post = findViewById(R.id.bt_post);

        bt_get.setOnClickListener(this);
        bt_post.setOnClickListener(this);
    }

    @Override
    public void onClick(View view) {
        switch (view.getId()) {
            case R.id.bt_get:
                run();
                try {
                    run();
                } catch (Exception e) {
                    e.printStackTrace();
                }
                break;
        }
    }

    private void getRequest() {

        final Request request = new Request.Builder()
                .get()
                .tag(this)
                .url("https://api.apiopen.top/recommendPoetry")
                .build();

        new Thread(new Runnable() {
            @Override
            public void run() {
                Response response = null;
                try {
                    response = client.newCall(request).execute();
                    if (response.isSuccessful()) {
                        Log.i("WY", "打印GET响应的数据：" + response.body().string());
                    } else {
                        throw new IOException("Unexpected code " + response);
                    }
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }).start();
    }

    public void run() {

        Request request = new Request.Builder()
                .url("https://api.jisuapi.com/tangshi/chapter?appkey=ccb0bd990f91c687")
                .get()
                .build();

        client.newCall(request).enqueue(new Callback() {

            @Override
            public void onFailure(Call call, IOException e) {
                e.printStackTrace();
            }

            @Override
            public void onResponse(Call call, Response response) throws IOException {
                if (!response.isSuccessful()) throw new IOException("Unexpected code " + response);

                String content = response.body().string();
                final List<PoetryModel> poetryModels = data(content);

                runOnUiThread(new Runnable() {
                    @Override
                    public void run() {
                        PoetryAdapter adapter = new PoetryAdapter(poetryModels);
                        recycler.setAdapter(adapter);

                        adapter.setOnItemClickListener(new PoetryAdapter.OnItemClickListener() {
                            @Override
                            public void onItemClick(PoetryModel poetryModel) {
                                Intent intent = new Intent(MainActivity.this,DetailActivity.class);
                                intent.putExtra("entity",poetryModel);
                                startActivity(intent);
                            }
                        });
                    }
                });
            }
        });
    }

    private List<PoetryModel> data(String content) {
        List<PoetryModel> poetryModels = new ArrayList<>();

        try {
            //解析json数组
            JSONObject jsonObject = new JSONObject(content);
            JSONArray jsonArray = jsonObject.optJSONArray("result");
            for (int i = 0; i < jsonArray.length(); i++) {
                JSONObject object = jsonArray.getJSONObject(i);

                if (object != null) {

                    int detailid = object.optInt("detailid");
                    String name = object.optString("name");
                    String author = object.optString("author");
                    // 封装Java对象
                    PoetryModel poetryModel = new PoetryModel(detailid, name, author);
                    //显示解析后的数据
                    poetryModels.add(poetryModel);

                    Log.d("PoetryTag", "detail:" + detailid + ", name:" + name + ", author:" + author);
                }
            }
        } catch (JSONException e) {
            e.printStackTrace();
        }
        return poetryModels;
    }
}

DetailAcivity:

public class DetailActivity extends AppCompatActivity {

    private TextView tv_title;
    private TextView tv_type;
    private TextView tv_content;
    private DetailModel detailModel;
    private PoetryModel poetryModel;

    private Handler handler = new Handler();

    final OkHttpClient client = new OkHttpClient();

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_detail);

        tv_title = findViewById(R.id.tv_title);
        tv_type = findViewById(R.id.tv_type);
        tv_content = findViewById(R.id.tv_content);

        poetryModel = getIntent().getParcelableExtra("entity");

        run(poetryModel.getDetailid());
    }

    public void run(int id) {
        Request request = new Request.Builder()
                .url("https://api.jisuapi.com/tangshi/detail?appkey=ccb0bd990f91c687&detailid=" + id)
                .get()
                .build();

        client.newCall(request).enqueue(new Callback() {

            @Override
            public void onFailure(Call call, IOException e) {
                e.printStackTrace();
            }

            @Override
            public void onResponse(Call call, Response response) throws IOException {
                if (!response.isSuccessful()) throw new IOException("Unexpected code " + response);

                //获取JSON数据
                final String content = response.body().string();

                JSONObject jsonObject = null;
                try {
                    //解析JSON对象
                    jsonObject = new JSONObject(content);
                    JSONObject result = jsonObject.optJSONObject("result");

                    final int detailid = result.optInt("detailid");
                    final String title = result.optString("title");
                    final String type = result.optString("type");
                    String c = result.optString("content");

                    // 封装Java对象
                    detailModel = new DetailModel(detailid, title, type, c);
                    System.out.println(detailModel);

                    handler.post(new Runnable() {
                        @Override
                        public void run() {
                            Log.d("PoetryTag", "detailid:" + detailid + ", title:" + title + ", type:" + type + ", content:" + content);
                            //显示解析后的数据
                            tv_title.setText(detailModel.getTitle());
                            tv_type.setText(detailModel.getType());
                            tv_content.setText(Html.fromHtml(detailModel.getContent()));
                        }
                    });
                } catch (JSONException e) {
                    e.printStackTrace();
                }
            }
        });
    }
}

运行结果：

image.png

image.png