Java 编程基础（入门级）超级完整版（2025 更新）

一、Java 开发环境搭建（2025 最新版）

1.1 采用 SDKMAN! 管理 JDK

使用 SDKMAN! 可以便捷切换不同版本的 JDK：

# 安装 SDKMAN!

curl -s "https://get.sdkman.io" | bash

source "$HOME/.sdkman/bin/sdkman-init.sh"

# 安装最新 LTS 版本 JDK

sdk install java 21.0.1-tem

1.2 使用 Visual Studio Code 开发 Java

安装 VS Code 并添加 Java 扩展包（Extension Pack for Java）

配置 Maven/Gradle 支持：

# 安装 Maven

sdk install maven

# 安装 Gradle

sdk install gradle

二、Java 17+ 新特性实战

2.1 文本块（Text Blocks）

public class TextBlockExample {

public static void main(String[] args) {

String html = """

Hello, Java 17!

""";

System.out.println(html);

}

}

2.2 Switch 表达式增强

public class SwitchExpression {

public static void main(String[] args) {

String day = "MONDAY";

int workHours = switch (day) {

case "MONDAY", "TUESDAY", "WEDNESDAY", "THURSDAY", "FRIDAY" -> 8;

case "SATURDAY", "SUNDAY" -> 0;

default -> throw new IllegalArgumentException("Invalid day: " + day);

};

System.out.println("Work hours: " + workHours);

}

}

2.3 Record 类

// 传统类

class Person {

private final String name;

private final int age;

public Person(String name, int age) {

this.name = name;

this.age = age;

}

public String getName() {

return name; }

public int getAge() {

return age; }

}

// Record 类 (Java 14+)

record PersonRecord(String name, int age) {

}

public class RecordExample {

public static void main(String[] args) {

PersonRecord person = new PersonRecord("Alice", 30);

System.out.println(person.name()); // 直接访问组件

}

}

三、面向对象编程进阶

3.1 接口默认方法与静态方法

interface Vehicle {

void start();

// 默认方法

default void honk() {

System.out.println("Beep! Beep!");

}

// 静态方法

static void emergencyStop() {

System.out.println("Emergency braking engaged!");

}

}

class Car implements Vehicle {

@Override

public void start() {

System.out.println("Car engine started");

}

}

3.2 抽象类与模板方法模式

abstract class Game {

// 模板方法

public final void play() {

initialize();

startPlay();

endPlay();

}

protected abstract void initialize();

protected abstract void startPlay();

protected abstract void endPlay();

}

class Cricket extends Game {

@Override

protected void initialize() {

System.out.println("Cricket Game Initialized! Start playing.");

}

@Override

protected void startPlay() {

System.out.println("Cricket Game Started. Enjoy the game!");

}

@Override

protected void endPlay() {

System.out.println("Cricket Game Finished!");

}

}

四、Java 集合框架深度应用

4.1 Stream API 高级操作

import java.util.Arrays;

import java.util.List;

import java.util.Map;

import java.util.stream.Collectors;

public class StreamExample {

public static void main(String[] args) {

List words = Arrays.asList("apple", "banana", "cherry", "date");

// 过滤长度大于5的单词并转为大写

List result = words.stream()

.filter(word -> word.length() > 5)

.map(String::toUpperCase)

.collect(Collectors.toList());

// 分组操作

Map> wordsByLength = words.stream()

.collect(Collectors.groupingBy(String::length));

System.out.println(result); // [BANANA, CHERRY]

System.out.println(wordsByLength); // {5=[apple, cherry, date], 6=[banana]}

}

}

4.2 并发集合应用

import java.util.concurrent.ConcurrentHashMap;

public class ConcurrentMapExample {

public static void main(String[] args) {

ConcurrentHashMap map = new ConcurrentHashMap<>();

// 多线程安全操作

map.put("key1", 1);

map.put("key2", 2);

// 原子性更新

map.computeIfAbsent("key3", k -> 3);

System.out.println(map); // {key1=1, key2=2, key3=3}

}

}

五、Java 17+ 新特性实战

5.1 模式匹配增强（Pattern Matching）

public class PatternMatchingExample {

public static void main(String[] args) {

Object obj = "Hello";

// 传统方式

if (obj instanceof String) {

String s = (String) obj;

System.out.println(s.length());

}

// 模式匹配方式 (Java 17+)

if (obj instanceof String s) {

System.out.println(s.length()); // 直接使用 s

}

}

}

5.2 密封类（Sealed Classes）

// 密封类

public sealed interface Shape

permits Circle, Rectangle, Square {

double area();

}

final class Circle implements Shape {

private final double radius;

public Circle(double radius) {

this.radius = radius;

}

@Override

public double area() {

return Math.PI * radius * radius;

}

}

final class Rectangle implements Shape {

private final double width;

private final double height;

public Rectangle(double width, double height) {

this.width = width;

this.height = height;

}

@Override

public double area() {

return width * height;

}

}

六、应用实例：现代学生成绩管理系统

6.1 使用 Maven 构建项目

xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">

4.0.0

com.example

student-management

1.0-SNAPSHOT

17

17

org.projectlombok

lombok

1.18.28

provided

com.h2database

h2

2.2.220

6.2 使用 Lombok 简化实体类

import lombok.AllArgsConstructor;

import lombok.Data;

import lombok.NoArgsConstructor;

@Data

@AllArgsConstructor

@NoArgsConstructor

public class Student {

private String id;

private String name;

private int age;

private double score;

}

6.3 数据库操作（使用 JDBC）

import java.sql.*;

import java.util.ArrayList;

import java.util.List;

public class StudentDAO {

private static final String URL = "jdbc:h2:./studentdb";

private static final String USER = "sa";

private static final String PASSWORD = "";

// 创建表

public void createTable() {

try (Connection conn = DriverManager.getConnection(URL, USER, PASSWORD);

Statement stmt = conn.createStatement()) {

String sql = "CREATE TABLE IF NOT EXISTS students (" +

"id VARCHAR(255) PRIMARY KEY, " +

"name VARCHAR(255), " +

"age INT, " +

"score DOUBLE)";

stmt.executeUpdate(sql);

} catch (SQLException e) {

e.printStackTrace();

}

}

// 添加学生

public void addStudent(Student student) {

String sql = "INSERT INTO students (id, name, age, score) VALUES (?, ?, ?, ?)";

try (Connection conn = DriverManager.getConnection(URL, USER, PASSWORD);

PreparedStatement pstmt = conn.prepareStatement(sql)) {

pstmt.setString(1, student.getId());

pstmt.setString(2, student.getName());

pstmt.setInt(3, student.getAge());

pstmt.setDouble(4, student.getScore());

pstmt.executeUpdate();

} catch (SQLException e) {

e.printStackTrace();

}

}

// 查询所有学生

public List getAllStudents() {

List students = new ArrayList<>();

String sql = "SELECT * FROM students";

try (Connection conn = DriverManager.getConnection(URL, USER, PASSWORD);

Statement stmt = conn.createStatement();

ResultSet rs = stmt.executeQuery(sql)) {

while (rs.next()) {

Student student = new Student(

rs.getString("id"),

rs.getString("name"),

rs.getInt("age"),

rs.getDouble("score")

);

students.add(student);

}

} catch (SQLException e) {

e.printStackTrace();

}

return students;

}

}

6.4 控制台界面（使用 JavaFX）

import javafx.application.Application;

import javafx.collections.FXCollections;

import javafx.collections.ObservableList;

import javafx.scene.Scene;

import javafx.scene.control.*;

import javafx.scene.control.cell.PropertyValueFactory;

import javafx.scene.layout.BorderPane;

import javafx.scene.layout.HBox;

import javafx.scene.layout.VBox;

import javafx.stage.Stage;

public class StudentManagementApp extends Application {

private TableView tableView = new TableView<>();

private ObservableList studentList = FXCollections.observableArrayList();

private StudentDAO studentDAO = new StudentDAO();

@Override

public void start(Stage primaryStage) {

studentDAO.createTable();

loadStudents();

// 设置表格

TableColumn idCol = new TableColumn<>("ID");

idCol.setCellValueFactory(new PropertyValueFactory<>("id"));

TableColumn nameCol = new TableColumn<>("Name");

nameCol.setCellValueFactory(new PropertyValueFactory<>("name"));

TableColumn ageCol = new TableColumn<>("Age");

ageCol.setCellValueFactory(new PropertyValueFactory<>("age"));

TableColumn scoreCol = new TableColumn<>("Score");

scoreCol.setCellValueFactory(new PropertyValueFactory<>("score"));

tableView.getColumns().addAll(idCol, nameCol, ageCol, scoreCol);

tableView.setItems(studentList);

// 添加学生表单

TextField idField = new TextField();

idField.setPromptText("ID");

TextField nameField = new TextField();

nameField.setPromptText("Name");

TextField ageField = new TextField();

ageField.setPromptText("Age");

TextField scoreField = new TextField();

scoreField.setPromptText("Score");

Button addButton = new Button("Add Student");

addButton.setOnAction(e -> {

try {

String id = idField.getText();

String name = nameField.getText();

int age = Integer.parseInt(ageField.getText());

double score = Double.parseDouble(scoreField.getText());

Student student = new Student(id, name, age, score);

studentDAO.addStudent(student);

studentList.add(student);

// 清空表单

idField.clear();

nameField.clear();

ageField.clear();

scoreField.clear();

} catch (NumberFormatException ex) {

Alert alert = new Alert(Alert.AlertType.ERROR);

alert.setTitle("Input Error");

alert.setContentText("Please enter valid age and score!");

alert.showAndWait();

}

});

HBox formBox = new HBox(10, idField, nameField, ageField, scoreField, addButton);

// 主布局

BorderPane root = new BorderPane();

root.setCenter(tableView);

root.setBottom(formBox);

Scene scene = new Scene(root, 800, 600);

primaryStage.setScene(scene);

primaryStage.setTitle("Student Management System");

primaryStage.show();

}

private void loadStudents() {

studentList.addAll(studentDAO.getAllStudents());

}

public static void main(String[] args) {

launch(args);

}

}

七、测试与调试技术

7.1 JUnit 5 单元测试

import static org.junit.jupiter.api.Assertions.*;

import org.junit.jupiter.api.Test;

class Calculator {

public int add(int a, int b) {

return a + b;

}

}

class CalculatorTest {

@Test

void testAdd() {

Calculator calculator = new Calculator();

int result = calculator.add(2, 3);

assertEquals(5, result);

}

}

7.2 使用日志框架（SLF4J + Logback）

org.slf4j

slf4j-api

2.0.9

ch.qos.logback

logback-classic

1.4.11

import org.slf4j.Logger;

import org.slf4j.LoggerFactory;

public class LogExample {

private static final Logger logger = LoggerFactory.getLogger(LogExample.class);

public static void main(String[] args) {

logger.info("程序启动");

try {

int result = 10 / 0;

} catch (Exception e) {

logger.error("发生异常: {}", e.getMessage(), e);

}

logger.info("程序结束");

}

}

八、进阶学习资源

官方文档：

Java 官方文档

OpenJDK 项目

推荐书籍：

《Effective Java》（第 3 版）

《Java 核心技术》（第 12 版）

《Java 并发编程实战》

在线课程：

Coursera: Java Programming and Software Engineering Fundamentals

Udemy: Java Masterclass for Software Developers

社区与论坛：

Stack Overflow

Reddit 的 r/java 板块

通过掌握这些内容，你将建立坚实的 Java 编程基础，并能够进一步学习高级主题如 Spring Boot、微服务和云原生开发。

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资源地址：https://pan.quark.cn/s/14fcf913bae6

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