第十三周总结
Java 学习第十三周总结
一、学习概述
本周学习内容涵盖 Android 应用架构设计、插件开发高级特性、性能优化以及 Java Web 基础技术。在 Android 领域，深入学习了 MVC、MVP、MVVM 及 Clean Architecture 等架构模式，并实践了微服务架构在 Android 中的应用；插件开发方面，掌握了代码生成、Gradle 集成等高级功能；性能优化聚焦应用启动优化与用户体验提升；同时学习了 Java Web 中的 Servlet 进阶与 JSP 技术。
二、Android 架构设计实践
- 经典架构模式对比
MVC、MVP、MVVM 架构实现
// MVP模式示例：LoginPresenter
public class LoginPresenter {
private LoginView view;
private LoginModel model;
public LoginPresenter(LoginView view) {
this.view = view;
this.model = new LoginModel();
}
public void login() {
view.showLoading();
String userName = view.getUserName();
String password = view.getPassword();
model.login(userName, password, new LoginCallback() {
@Override
public void onSuccess() {
view.loginSuccess();
view.hideLoading();
}
@Override
public void onFailure(String errorMsg) {
view.loginFailed(errorMsg);
view.hideLoading();
}
});
}
}
// MVVM模式示例：LoginViewModel
public class LoginViewModel extends ViewModel {
private MutableLiveData
private MutableLiveData
private MutableLiveData<Resource
private LoginRepository repository;
public LoginViewModel(LoginRepository repository) {
this.repository = repository;
}
public void login() {
loginResult.setValue(Resource.loading(null));
String user = username.getValue();
String pwd = password.getValue();
repository.login(user, pwd, new LoginCallback() {
@Override
public void onSuccess(User user) {
loginResult.setValue(Resource.success(user));
}
@Override
public void onFailure(String error) {
loginResult.setValue(Resource.error(error, null));
}
});
}
}
Clean Architecture 分层实践
project/
├── app/
│ ├── src/
│ │ ├── main/
│ │ │ ├── java/
│ │ │ │ ├── com/example/clean/
│ │ │ │ │ ├── entity/ # 实体层：User.java
│ │ │ │ │ ├── usecase/ # 用例层：LoginUseCase.java
│ │ │ │ │ ├── data/ # 数据层
│ │ │ │ │ │ ├── repository/ # 仓库：LoginRepository.java
│ │ │ │ │ │ ├── local/ # 本地数据源
│ │ │ │ │ │ └── remote/ # 远程数据源
│ │ │ │ │ └── ui/ # UI层：LoginActivity.java
│ │ │ └── res/
│ └── build.gradle
└── gradle/
2. 微服务架构探索
认证微服务实现
// 服务接口定义
public interface AuthService {
void login(String username, String password, LoginCallback callback);
void logout(String userId, LogoutCallback callback);
interface LoginCallback {
void onSuccess(User user);
void onFailure(String error);
}
}
// 服务实现
public class AuthServiceImpl implements AuthService {
private OkHttpClient client = new OkHttpClient();
private Gson gson = new Gson();
@Override
public void login(String username, String password, LoginCallback callback) {
RequestBody body = new FormBody.Builder()
.add("username", username)
.add("password", password)
.build();
Request request = new Request.Builder()
.url("https://api/auth/login")
.post(body)
.build();
client.newCall(request).enqueue(new Callback() {
@Override
public void onResponse(Call call, Response response) {
if (response.isSuccessful()) {
User user = gson.fromJson(response.body().string(), User.class);
callback.onSuccess(user);
} else {
callback.onFailure("登录失败");
}
}
});
}
}
服务通信与数据一致性
// 事件发布器
public class EventPublisher {
private Connection connection;
private Channel channel;
public EventPublisher() throws IOException {
ConnectionFactory factory = new ConnectionFactory();
factory.setHost("localhost");
connection = factory.newConnection();
channel = connection.createChannel();
channel.queueDeclare("event_queue", true, false, false, null);
}
public void publish(String eventType, String data) throws IOException {
String message = "{\"type\":\"" + eventType + "\",\"data\":" + data + "}";
channel.basicPublish("", "event_queue", null, message.getBytes());
}
}
// 事件消费者
public class EventConsumer {
public void consume(EventCallback callback) {
new Thread(() -> {
try {
ConnectionFactory factory = new ConnectionFactory();
factory.setHost("localhost");
Connection connection = factory.newConnection();
Channel channel = connection.createChannel();
channel.queueDeclare("event_queue", true, false, false, null);
channel.basicConsume("event_queue", false, (tag, delivery) -> {
String event = new String(delivery.getBody());
callback.onEvent(event);
channel.basicAck(delivery.getEnvelope().getDeliveryTag(), false);
}, tag -> {});
} catch (Exception e) {
e.printStackTrace();
}
}).start();
}
}
三、Android 插件开发高级特性
- 智能代码生成
Activity 生成插件实现
// 模板引擎
public class TemplateEngine {
private Configuration config;
public TemplateEngine() {
config = new Configuration(new ClassTemplateLoader(getClass(), "/templates"));
}
public String process(String templateName, Map<String, Object> data)
throws TemplateException, IOException {
Template template = config.getTemplate(templateName);
StringWriter writer = new StringWriter();
template.process(data, writer);
return writer.toString();
}
}
// 生成器
public class ActivityGenerator {
private TemplateEngine engine = new TemplateEngine();
public void generate(Project project, String pkg, String name) {
try {
Map<String, Object> data = new HashMap<>();
data.put("package", pkg);
data.put("activityName", name);
data.put("layoutName", "activity_" + name.toLowerCase());
// 生成Java代码
String javaCode = engine.process("activity.ftl", data);
writeToFile(project, "java/" + pkg.replace('.', '/') + "/" + name + ".java", javaCode);
// 生成布局文件
String layoutCode = engine.process("layout.ftl", data);
writeToFile(project, "res/layout/" + "activity_" + name.toLowerCase() + ".xml", layoutCode);
} catch (Exception e) {
e.printStackTrace();
}
}
}
2. Gradle 集成功能
依赖自动配置
public class GradleDependencyManager {
private Project project;
public GradleDependencyManager(Project project) {
this.project = project;
}
public void addDependency(String modulePath, String dependency) {
File buildFile = new File(project.getBasePath() + modulePath + "/build.gradle");
if (!buildFile.exists()) return;
try {
String content = Files.readString(Paths.get(buildFile.toURI()));
if (content.contains(dependency)) return;
String newContent = content.replace(
"dependencies {",
"dependencies {\n " + dependency + "\n"
);
Files.writeString(Paths.get(buildFile.toURI()), newContent);
GradleProjectImporter.getInstance().refreshProject(project);
} catch (IOException e) {
e.printStackTrace();
}
}
}
四、性能优化与用户体验
- 启动性能优化
启动流程优化
public class AppStartup {
private static final long DELAY_NON_CRITICAL = 1500; // 非关键任务延迟1.5秒
public void init(final Context context) {
// 关键任务 - 主线程执行
initCoreComponents(context);
// 非关键任务 - 子线程延迟执行
new Handler(Looper.getMainLooper()).postDelayed(() -> {
new Thread(() -> {
initAnalytics();
initThirdPartyServices();
}).start();
}, DELAY_NON_CRITICAL);
}
private void initCoreComponents(Context context) {
// 初始化UI框架、数据库连接等关键组件
}
private void initAnalytics() {
// 初始化统计分析组件
}
}
启动性能监控
public class StartupMonitor {
private static final String TAG = "StartupMonitor";
private long startTime;
public void start() {
startTime = System.currentTimeMillis();
}
public void logStage(String stage) {
long elapsed = System.currentTimeMillis() - startTime;
Log.d(TAG, stage + " took: " + elapsed + "ms");
}
public void finish() {
long elapsed = System.currentTimeMillis() - startTime;
Log.d(TAG, "Total startup time: " + elapsed + "ms");
}
}
2. 用户体验优化
交互反馈优化
public class FeedbackButton extends AppCompatButton {
private static final float SCALE = 0.9f;
private static final long DURATION = 150;
public FeedbackButton(Context context) {
super(context);
init();
}
private void init() {
setOnTouchListener((v, event) -> {
if (event.getAction() == MotionEvent.ACTION_DOWN) {
scaleX = SCALE;
scaleY = SCALE;
postDelayed(() -> {
scaleX = 1f;
scaleY = 1f;
}, DURATION);
}
return false;
});
}
}
手势操作支持
public class GestureHandler implements OnTouchListener {
private GestureDetector detector;
private OnSwipeListener listener;
public GestureHandler(OnSwipeListener listener) {
this.listener = listener;
detector = new GestureDetector(new GestureAdapter());
}
@Override
public boolean onTouch(View v, MotionEvent event) {
detector.onTouchEvent(event);
return true;
}
private class GestureAdapter extends SimpleOnGestureListener {
@Override
public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
float diffX = e1.getX() - e2.getX();
if (diffX > 100 && Math.abs(velocityX) > 200) {
listener.onSwipeLeft();
return true;
} else if (-diffX > 100 && Math.abs(velocityX) > 200) {
listener.onSwipeRight();
return true;
}
return false;
}
}
public interface OnSwipeListener {
void onSwipeLeft();
void onSwipeRight();
}
}
五、Java Web 基础技术
- Servlet 进阶
Servlet 配置与生命周期
// 注解配置
@WebServlet(
name = "LoginServlet",
urlPatterns = "/login",
initParams = {
@WebInitParam(name = "dbUrl", value = "jdbc:mysql://localhost/db"),
@WebInitParam(name = "dbUser", value = "user")
}
)
public class LoginServlet extends HttpServlet {
private String dbUrl;
private String dbUser;
@Override
public void init(ServletConfig config) throws ServletException {
super.init(config);
dbUrl = config.getInitParameter("dbUrl");
dbUser = config.getInitParameter("dbUser");
System.out.println("Servlet initialized with db: " + dbUrl);
}
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
String username = request.getParameter("username");
String password = request.getParameter("password");
// 处理登录逻辑
response.getWriter().write("Login processed for: " + username);
}
@Override
public void destroy() {
System.out.println("Servlet destroyed, cleaning resources");
}
}
2. JSP 技术应用
JSP 指令与内置对象
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@ include file="header.jsp" %>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
Welcome, <%= request.getParameter("username") %>
<%
session.setAttribute("lastVisit", new Date());
application.setAttribute("onlineUsers",
(Integer)application.getAttribute("onlineUsers") + 1);
%>
<p>Last visit: ${sessionScope.lastVisit}</p>
<p>Online users: ${applicationScope.onlineUsers}</p>
<c:if test="${not empty param.error}">
<div class="error">${param.error}</div>
</c:if>
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