Hutool 工具包

基本信息

• Hutool 是一个小而全的Java工具类库
• API 文档https://apidoc.gitee.com/dromara/hutool/

2. 实战

• 一般引用 hutool-core，如果要用全部 hutool-all

<dependency>
    <groupId>cn.hutool</groupId>
    <artifactId>hutool-core</artifactId>
    <version>5.6.5</version>
</dependency>

2.1 读取文件

• FileUtil.readString(url, CharsetUtil.UTF_8);
• FileUtil.readUtf8String(path);

@Test
public void readFile() {
    // resources 目录下
    String fileName = "user.json";
    String str = FileUtil.readUtf8String(fileName);
    JSONObject jsonObj = JSON.parseObject(str);
}

@Test
public void readFile2() {
    String fileName = "user.json";
    URL url = Thread.currentThread().getContextClassLoader().getResource(fileName);
    String str = FileUtil.readUtf8String(url.getPath());
    JSONObject jsonObj = JSON.parseObject(str);
}

2.2 写入文件

• 追加模式 FileUtil.appendUtf8String(str, path);

@Test
public void writeFile() {
    List<String> values = Arrays.asList("aaa", "bbb", "中文");
    String path = "/Users/.../resources/demo.txt";
    values.forEach(str -> FileUtil.appendUtf8String(str + "\r\n", path));
}

获取项目目录，并添加文件

@Test
public void writeFile2() {
    String fileName = "application.yml";
    URL url = Thread.currentThread().getContextClassLoader().getResource(fileName);
    String path = url.getPath();
    String filePath = path.substring(0, path.indexOf("/target/classes")) + "/files/demo.txt";

    List<String> values = Arrays.asList("aaa", "bbb", "中文");
    values.forEach(str -> {
        FileUtil.appendUtf8String(str, filePath);
        FileUtil.appendUtf8String("\r\n", filePath);
    });
}

@Test
public void replaceFile() {
    String fileName = "user.json";
    URL url = Thread.currentThread().getContextClassLoader().getResource(fileName);
    String filePath = url.getPath()
            .replaceAll("target/classes", "src/main/resources/files")
            .replaceAll("\\.json", "\\.txt");

    String content = FileUtil.readUtf8String(fileName);
    JSONObject jsonObj = JSON.parseObject(content);
    // for (Map.Entry<String, Object> entry : jsonObj.entrySet()) {
    //
    // }
    // forEach(BiConsumer) --> void accept(T t, U u);
    jsonObj.forEach((str, obj) -> {
        FileUtil.appendUtf8String(str + ", value=" + obj, filePath);
        FileUtil.appendUtf8String("\r\n", filePath);
    });
}