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在Android开发中，有时候需要在应用程序中嵌入一个浏览器来展示网页，而不允许用户直接打开系统浏览器。WebView控件正是用来实现这一需求的。
在布局文件中添加WebView控件
在Android项目的布局文件中添加WebView控件，通常使用XML结构如下：在活动中获取WebView实例
在Activity类中找到WebView控件，并设置其支持JavaScript：public class MainActivity extends AppCompatActivity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); WebView webView = (WebView) findViewById(R.id.web_view); webView.getSettings().setJavaScriptEnabled(true); } }让WebView支持JavaScript
WebView默认不支持JavaScript，可以通过设置setJavaScriptEnabled(true)来启用：webView.getSettings().setJavaScriptEnabled(true);
让网页在WebView中打开
使用loadUrl方法加载网页：webView.loadUrl("https://www.baidu.com");传入网址
需要注意的是，loadUrl方法会自动处理HTTP和HTTPS URL。完整的实现代码如下：
public class MainActivity extends AppCompatActivity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); WebView webView = (WebView) findViewById(R.id.web_view); webView.getSettings().setJavaScriptEnabled(true); webView.setWebViewClient(new WebViewClient()); webView.loadUrl("https://www.baidu.com"); } } HTTP协议是客户端和服务器之间进行通信的标准协议。Android上发送HTTP请求有两种常用方式：HttpURLConnection 和 OkHttp。
public class MainActivity extends AppCompatActivity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); final Button button = (Button) findViewById(R.id.button); final TextView textView = (TextView) findViewById(R.id.text); button.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View view) { new Thread(new Runnable() { @Override public void run() { try { URL url = new URL("https://www.baidu.com"); HttpURLConnection connection = (HttpURLConnection) url.openConnection(); connection.setRequestMethod("GET"); connection.setReadTimeout(8000); connection.setConnectTimeout(8000); InputStream in = connection.getInputStream(); BufferedReader reader = new BufferedReader(new InputStreamReader(in)); final StringBuilder content = new StringBuilder(); String line; while ((line = reader.readLine()) != null) { content.append(line); } MainActivity.this.runOnUiThread(new Runnable() { @Override public void run() { textView.setText(content.toString()); } }); } catch (Exception e) { e.printStackTrace(); } finally { if (reader != null) { try { reader.close(); } catch (IOException e) { e.printStackTrace(); } } if (connection != null) { connection.disconnect(); } } } }).start(); } }); } } 如果需要提交数据，可以将HTTP方法设置为POST，并添加请求体：
connection.setRequestMethod("POST"); DataOutputStream out = new DataOutputStream(connection.getOutputStream()); out.writeBytes("username=admin&password=123456"); 在项目的build.gradle中添加OkHttp依赖：
implementation 'com.squareup.okhttp3:okhttp:4.8.1'
public class MainActivity extends AppCompatActivity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); final Button button = (Button) findViewById(R.id.button); final TextView textView = (TextView) findViewById(R.id.text); button.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View view) { new Thread(new Runnable() { @Override public void run() { try { OkHttpClient client = new OkHttpClient(); Request request = new Request.Builder() .url("https://www.baidu.com") .build(); Response response = client.newCall(request).execute(); final String content = response.body().string(); MainActivity.this.runOnUiThread(new Runnable() { @Override public void run() { textView.setText(content); } }); } catch (Exception e) { e.printStackTrace(); } } }).start(); } }); } } 如果需要提交数据，可以通过OkHttp的post()方法：
RequestBody requestBody = new FormBody.Builder() .add("username", "admin") .add("password", "123456") .build(); Request request = new Request.Builder() .url("https://www.baidu.com") .post(requestBody) .build(); 在网络传输中，XML是常用的数据格式。Android支持两种解析方式：Pull解析和SAX解析。
private void parseXMLWithPull(String xmlData) { try { XmlPullParserFactory factory = XmlPullParserFactory.newInstance(); XmlPullParser parser = factory.newPullParser(); parser.setInput(new StringReader(xmlData)); int eventType = parser.getEventType(); String id = ""; String name = ""; String version = ""; while (eventType != XmlPullParser.END_DOCUMENT) { String nodeName = parser.getName(); switch (eventType) { case XmlPullParser.START_TAG: { if ("id".equals(nodeName)) { id = parser.nextText(); } else if ("name".equals(nodeName)) { name = parser.nextText(); } else if ("version".equals(nodeName)) { version = parser.nextText(); } break; } case XmlPullParser.END_TAG: { if ("app".equals(nodeName)) { Log.e("MainActivity", id); Log.e("MainActivity", name); Log.e("MainActivity", version); } break; } default: break; } eventType = parser.next(); } } catch (Exception e) { e.printStackTrace(); } } public class MyHandler extends DefaultHandler { StringBuilder id; StringBuilder name; StringBuilder version; String nodeName; @Override public void startDocument() throws SAXException { super.startDocument(); id = new StringBuilder(); name = new StringBuilder(); version = new StringBuilder(); } @Override public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException { super.startElement(uri, localName, qName, attributes); nodeName = localName; } @Override public void characters(char[] ch, int start, int length) throws SAXException { super.characters(ch, start, length); if ("id".equals(nodeName)) { id.append(ch, start, length); } else if ("name".equals(nodeName)) { name.append(ch, start, length); } else if ("version".equals(nodeName)) { version.append(ch, start, length); } } @Override public void endElement(String uri, String localName, String qName) throws SAXException { super.endElement(uri, localName, qName); if ("app".equals(nodeName)) { Log.e("MyHandler", id.toString().trim()); Log.e("MyHandler", name.toString().trim()); Log.e("MyHandler", version.toString().trim()); } id.setLength(0); name.setLength(0); version.setLength(0); } @Override public void endDocument() throws SAXException { super.endDocument(); } } private void parseXMLWithSAX(String xmlData) { try { SAXParserFactory factory = SAXParserFactory.newInstance(); XMLReader reader = factory.newSAXParser().getXMLReader(); MyHandler myHandler = new MyHandler(); reader.setDTDHandler(myHandler); reader.parse(new InputSource(new StringReader(xmlData))); } catch (Exception e) { e.printStackTrace(); } } JSON格式的数据解析可以使用JSONObject或GSON库。
private void parseJSONWithJSONObject(String jsonData) { try { JSONArray array = new JSONArray(jsonData); for (int i = 0; i < array.length(); i++) { JSONObject obj = array.optJSONObject(i); String id = obj.optString("id"); String name = obj.optString("name"); String version = obj.optString("version"); Log.e("MainActivity", id); Log.e("MainActivity", name); Log.e("MainActivity", version); } } catch (Exception e) { e.printStackTrace(); } } public class App { private String id; private String name; private String version; public String getId() { return id; } public void setId(String id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public String getVersion() { return version; } public void setVersion(String version) { this.version = version; } } Gson gson = new Gson(); Listapps = gson.fromJson(jsonData, new TypeToken
>() {}.getType()); for (App app : apps) { Log.e("MainActivity", app.getId()); Log.e("MainActivity", app.getName()); Log.e("MainActivity", app.getVersion()); }
public interface HttpCallbackListener { void onFinish(String response); void onError(Exception e); } public class HttpUtil { public static void sendHttpRequest(String address, HttpCallbackListener listener) { new Thread(new Runnable() { @Override public void run() { HttpURLConnection connection = null; BufferedReader reader = null; try { URL url = new URL(address); connection = (HttpURLConnection) url.openConnection(); connection.setRequestMethod("GET"); connection.setReadTimeout(8000); connection.setConnectTimeout(8000); InputStream in = connection.getInputStream(); BufferedReader reader = new BufferedReader(new InputStreamReader(in)); StringBuilder content = new StringBuilder(); String line; while ((line = reader.readLine()) != null) { content.append(line); } if (listener != null) { listener.onFinish(content.toString()); } } catch (Exception e) { if (listener != null) { listener.onError(e); } } finally { if (reader != null) { try { reader.close(); } catch (IOException e) { e.printStackTrace(); } } if (connection != null) { connection.disconnect(); } } } }).start(); } } public void onClick(View view) { HttpUtil.sendHttpRequest(address, new HttpCallbackListener() { @Override public void onFinish(String response) { // 处理成功响应 } @Override public void onError(Exception e) { // 处理异常 } }); } public class HttpUtil { public static void sendOkHttpRequest(String address, okhttp3.Callback callback) { OkHttpClient client = new OkHttpClient(); Request request = new Request.Builder() .url(address) .build(); client.newCall(request).enqueue(callback); } } public void onClick(View view) { HttpUtil.sendOkHttpRequest(address, new okhttp3.Callback() { @Override public void onFailure(Call call, IOException e) { // 处理失败 } @Override public void onResponse(Call call, Response response) throws IOException { // 处理成功响应 String responseData = response.body().string(); } }); } 通过以上方法，可以更高效地处理网络请求，并在UI线程上更新UI组件。
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