Java获取文件路径的几种方式汇总

import java.io.File;
import java.io.IOException;

public class FilePathDemo {
    public static void main(String[] args) throws IOException {
        // 1. 使用相对路径创建File对象
        File relativeFile = new File("data/config.properties");
        System.out.println("=== 相对路径示例 ===");
        System.out.println("getPath(): " + relativeFile.getPath());
        System.out.println("getAbsolutePath(): " + relativeFile.getAbsolutePath());
        System.out.println("getCanonicalPath(): " + relativeFile.getCanonicalPath());

        // 2. 使用包含".."的相对路径
        File complexRelativeFile = new File("./src/../data/config.properties");
        System.out.println("\n=== 复杂相对路径示例 ===");
        System.out.println("getPath(): " + complexRelativeFile.getPath());
        System.out.println("getAbsolutePath(): " + complexRelativeFile.getAbsolutePath());
        System.out.println("getCanonicalPath(): " + complexRelativeFile.getCanonicalPath());

        // 3. 使用绝对路径创建File对象
        File absoluteFile = new File("C:\\Users\\Public\\data\\config.properties"); // Windows路径示例
        System.out.println("\n=== 绝对路径示例 ===");
        System.out.println("getPath(): " + absoluteFile.getPath());
        System.out.println("getAbsolutePath(): " + absoluteFile.getAbsolutePath());
        System.out.println("getCanonicalPath(): " + absoluteFile.getCanonicalPath());
        
        // 获取父路径和文件名
        System.out.println("\n=== 路径元素获取 ===");
        System.out.println("父路径: " + relativeFile.getParent());
        System.out.println("文件名: " + relativeFile.getName());
    }
}

=== 相对路径示例 ===
getPath(): data\config.properties
getAbsolutePath(): D:\myproject\data\config.properties
getCanonicalPath(): D:\myproject\data\config.properties

=== 复杂相对路径示例 ===
getPath(): .\src\..\data\config.properties
getAbsolutePath(): D:\myproject\.\src\..\data\config.properties
getCanonicalPath(): D:\myproject\data\config.properties

=== 绝对路径示例 ===
getPath(): C:\Users\Public\data\config.properties
getAbsolutePath(): C:\Users\Public\data\config.properties
getCanonicalPath(): C:\Users\Public\data\config.properties

=== 路径元素获取 ===
父路径: data
文件名: config.properties

import java.nio.file.Path;
import java.nio.file.Paths;
import java.io.IOException;

public class NioPathDemo {
    public static void main(String[] args) throws IOException {
        // 1. 创建Path对象
        Path path = Paths.get("data", "config.properties");
        System.out.println("Path对象: " + path);

        // 2. 获取绝对路径
        Path absolutePath = path.toAbsolutePath();
        System.out.println("绝对路径: " + absolutePath);

        // 3. 获取规范路径 (解析符号链接)
        Path realPath = path.toRealPath();
        System.out.println("规范路径: " + realPath);
        
        // 4. 路径拼接
        Path basePath = Paths.get("D:", "projects");
        Path fullPath = basePath.resolve("myapp/config.properties");
        System.out.println("拼接后的路径: " + fullPath);
    }
}

import java.io.InputStream;
import java.util.Properties;

public class ResourceLoader {
    public static void main(String[] args) throws Exception {
        // 方法1: 使用Class.getResourceAsStream
        // 路径以 "/" 开头，表示从类路径根目录查找
        InputStream inputStream1 = ResourceLoader.class.getResourceAsStream("/config.properties");
        
        // 方法2: 使用ClassLoader.getResourceAsStream
        // 路径不以 "/" 开头，同样从类路径根目录查找
        InputStream inputStream2 = ResourceLoader.class.getClassLoader().getResourceAsStream("config.properties");

        if (inputStream1 != null) {
            Properties props = new Properties();
            props.load(inputStream1);
            System.out.println("成功加载配置: " + props.getProperty("app.name"));
            inputStream1.close();
        }
    }
}

public class SystemPathDemo {
    public static void main(String[] args) {
        System.out.println("当前工作目录: " + System.getProperty("user.dir"));
        System.out.println("用户主目录: " + System.getProperty("user.home"));
        System.out.println("Java安装目录: " + System.getProperty("java.home"));
    }
}

import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

public class PathServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException {
        // 获取Web应用在服务器上的物理根路径
        String realPath = request.getSession().getServletContext().getRealPath("/");
        response.getWriter().println("服务器物理路径: " + realPath);
        
        // 获取应用的上下文路径 (例如 /myapp)
        String contextPath = request.getContextPath();
        response.getWriter().println("应用上下文路径: " + contextPath);
    }
}