安卓前端连接springboot后端

本文仅记录安卓如何通过get请求获取springboot后端传来的json数据并解析，对springboot后端如何编写暂无涉及

准备好工具类HTTPUtils,此工具类用于连接后端的所要求的path路径，只需填入url路径即可，会返回后端传来的String字符串数据

请先在AndroidManifest.xml文件中添加网络允许设置

public class HttpUtils {
    

    public static String gethttpresult(String urlStr) {
        try {
            URL url = new URL(urlStr);//获取url对象
            HttpURLConnection connect = (HttpURLConnection) url.openConnection();//url对象进行http连接
            InputStream input = connect.getInputStream();
            BufferedReader in = new BufferedReader(new InputStreamReader(input));
            String line = null;
            System.out.println(connect.getResponseCode());
            StringBuffer sb = new StringBuffer();
            while ((line = in.readLine()) != null) {
                sb.append(line);//逐行读取传来的String
            }
            return sb.toString();
        } catch (Exception e) {
            System.out.println(e.toString());
            return null;
        }
    }
}

将传来的数据转化为JSON，并通过解析JSON来实现相当于读取数据库数据的目的

String result = httpUtil.gethttpresult(url);//利用工具类获取网络连接
JSonArray post_all = new JSONArray(result);//将返回的数据转换为JSON串格式
//                        JSonArray post_all = result_json.getJSonArray("post_all");
for (int i = 0; i < post_all.length(); i++) {
    post post_data = new post();//实例化post对象，用于存装从JSON解析出来的数据
	JSonObject object = post_all.getJSONObject(i);
	post_data.post_id = Integer.parseInt(object.getString("post_id"));
	post_data.post_context = object.getString("post_context");
	post_data.post_star = Integer.parseInt(object.getString("post_star"));
	post_data.post_replay = Integer.parseInt(object.getString("post_replay"));
	post_list.add(post_data);//将一个个装好JSON数据的对象加入到对象list中
}

应用举例

springboot的Controller层接口

@Controller
@RequestMapping("/post")
@ResponseBody
public class showPostController {
    @Autowired
    GetPostServiceImpl getPostService;

    @RequestMapping("/post_main")
    @ResponseBody
    public List getAllPost(HttpSession session, ModelMap map) {
        List post_all = new ArrayList<>();
        post post_data;
        int post_count = getPostService.getPostCount();
        for (int i = 1; i <= post_count; i++) {
            post_data = getPostService.getPost(i);
            post_all.add(post_data);
        }
        System.out.println(post_all);
        map.addAttribute("post_all", post_all);
        return post_all;
    }

可见路径为http://localhost:8080/post/post_main，返回的是从数据库中提取的List对象数组，其中post为自己设置的实例化对象，对应数据库中的一张表。

Activity的应用代码

public class HoleActivity extends AppCompatActivity {
    HoleAdapter mMyAdapter;
    RecyclerView mRecyclerView;
    List post_list = new ArrayList<>();
    HttpUtils httpUtil;

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

        String url = "http://yourip:8080/post/post_main";//此处改为自己的路径

        
        new Thread() {
            @Override
            public void run() {
                String result = httpUtil.gethttpresult(url);//利用工具类获取网络连接
                System.out.println(result);
                if (result == null) {
                    Looper.prepare();
                    Toast.makeText(HoleActivity.this, "网络连接错误！", Toast.LENGTH_SHORT).show();
                    Looper.loop();
                } else {
                    try {
                        JSonArray post_all = new JSONArray(result);//将返回的数据转换为JSON串格式
//                        JSonArray post_all = result_json.getJSonArray("post_all");
                        for (int i = 0; i < post_all.length(); i++) {
                            post post_data = new post();//实例化post对象，用于存装从JSON解析出来的数据
                            JSonObject object = post_all.getJSONObject(i);
                            post_data.post_id = Integer.parseInt(object.getString("post_id"));
                            post_data.post_context = object.getString("post_context");
                            post_data.post_star = Integer.parseInt(object.getString("post_star"));
                            post_data.post_replay = Integer.parseInt(object.getString("post_replay"));

                            post_list.add(post_data);//将一个个装好JSON数据的对象加入到对象list中
                        }


                    } catch (JSONException e) {
                        e.printStackTrace();
                        System.out.println(e.toString());
                        Looper.prepare();
                        Toast.makeText(HoleActivity.this, "文件解析错误！", Toast.LENGTH_SHORT).show();
                        Looper.loop();
                    }
                }

            }
        }.start();

        //获取RecyclerView对象
        mRecyclerView = findViewById(R.id.hole_rv);


        //设置adapter
        mMyAdapter = new HoleAdapter(HoleActivity.this, post_list);
        mRecyclerView.setAdapter(mMyAdapter);

        //设置layoutManager
        LinearLayoutManager layoutManager = new LinearLayoutManager(HoleActivity.this);
        mRecyclerView.setLayoutManager(layoutManager);

        //设置Decoration分割线
        DividerItemDecoration decoration = new DividerItemDecoration(this, DividerItemDecoration.VERTICAL);
        decoration.setDrawable(getResources().getDrawable(R.drawable.divider, null));
        mRecyclerView.addItemDecoration(decoration);


    }
}

END