Code片段 ： .properties属性文件操作工具类 & JSON工具类

摘要: 原创出处:www.bysocket.com 泥瓦匠BYSocket 希望转载，保留摘要，谢谢！ “贵专” — 泥瓦匠

一、java.util.Properties API & 案例

java.util.Properties 是一个属性集合。常见的api有如下：

• load(InputStream inStream)  从输入流中读取属性
• getProperty(String key)  根据key，获取属性值
• getOrDefault(Object key, V defaultValue) 根据key对象，获取属性值需要强转

首先在resources目录下增加/main/resources/fast.properties：

fast.framework.name=fast
fast.framework.author=bysocket
fast.framework.age=1

然后直接上代码PropertyUtil.java：

/**
 * .properties属性文件操作工具类
 *
 * Created by bysocket on 16/7/19.
 */
public class PropertyUtil {

    private static final Logger LOGGER = LoggerFactory.getLogger(PropertyUtil.class);

    /** .properties属性文件名后缀 */
    public static final String PROPERTY_FILE_SUFFIX	= ".properties";

    /**
     * 根据属性文件名,获取属性
     *
     * @param propsFileName
     * @return
     */
    public static Properties getProperties(String propsFileName) {
        if (StringUtils.isEmpty(propsFileName))
            throw new IllegalArgumentException();

        Properties  properties  = new Properties();
        InputStream inputStream = null;

        try {

            try {
                /** 加入文件名后缀 */
                if (propsFileName.lastIndexOf(PROPERTY_FILE_SUFFIX) == -1) {
                    propsFileName += PROPERTY_FILE_SUFFIX;
                }

                inputStream = Thread.currentThread().getContextClassLoader()
                        .getResourceAsStream(propsFileName);
                if (null != inputStream)
                    properties.load(inputStream);
            } finally {
                if ( null != inputStream) {
                    inputStream.close();
                }
            }

        } catch (IOException e) {
            LOGGER.error("加载属性文件出错!",e);
            throw new RuntimeException(e);
        }

        return properties;
    }

    /**
     * 根据key,获取属性值
     *
     * @param properties
     * @param key
     * @return
     */
    public static String getString(Properties properties, String key){
        return properties.getProperty(key);
    }

    /**
     * 根据key,获取属性值
     *
     * @param properties
     * @param key
     * @param defaultValue
     * @return
     */
    public static String getStringOrDefault(Properties properties, String key, String defaultValue){
        return properties.getProperty(key,defaultValue);
    }

    /**
     * 根据key,获取属性值
     *
     * @param properties
     * @param key
     * @param defaultValue
     * @param <V>
     * @return
     */
    public static <V> V getOrDefault(Properties properties, String key, V defaultValue){
        return (V) properties.getOrDefault(key,defaultValue);
    }
}

UT如下：

/**
 * {@link PropertyUtil} 测试用例
 * <p/>
 * Created by bysocket on 16/7/19.
 */
public class PropertyUtilTest {

    @Test
    public void testGetProperties() {
        Properties properties = PropertyUtil.getProperties("fast");
        String fastFrameworkName = properties.getProperty("fast.framework.name");
        String authorName        = properties.getProperty("fast.framework.author");
        Object age               = properties.getOrDefault("fast.framework.age",10);
        Object defaultVal        = properties.getOrDefault("fast.framework.null",10);
        System.out.println(fastFrameworkName);
        System.out.println(authorName);
        System.out.println(age.toString());
        System.out.println(defaultVal.toString());
    }

    @Test
    public void testGetString() {
        Properties properties = PropertyUtil.getProperties("fast");
        String fastFrameworkName = PropertyUtil.getString(properties,"fast.framework.name");
        String authorName        = PropertyUtil.getString(properties,"fast.framework.author");
        System.out.println(fastFrameworkName);
        System.out.println(authorName);
    }

    @Test
    public void testGetOrDefault() {
        Properties properties = PropertyUtil.getProperties("fast");
        Object age               = PropertyUtil.getOrDefault(properties,"fast.framework.age",10);
        Object defaultVal        = PropertyUtil.getOrDefault(properties,"fast.framework.null",10);
        System.out.println(age.toString());
        System.out.println(defaultVal.toString());
    }
}

Run Console:

1
10
fast
bysocket
1
10
fast
bysocket

相关对应代码分享在 Github 主页

二、JACKSON 案例

首先，加个Maven 依赖:

                <!-- Jackson -->
		<dependency>
			<groupId>org.codehaus.jackson</groupId>
			<artifactId>jackson-mapper-asl</artifactId>
			<version>1.9.13</version>
		</dependency>
		<dependency>
			<groupId>org.codehaus.jackson</groupId>
			<artifactId>jackson-jaxrs</artifactId>
			<version>1.9.13</version>
		</dependency>

然后直接上代码JSONUtil：

/**
 * JSON 工具类
 * <p/>
 * Created by bysocket on 16/7/19.
 */
public class JSONUtil {

    private static final Logger LOGGER = LoggerFactory.getLogger(JSONUtil.class);

    /**
     * 默认JSON类
     **/
    private static final ObjectMapper mapper = new ObjectMapper();

    /**
     * 将 Java 对象转换为 JSON 字符串
     *
     * @param object
     * @param <T>
     * @return
     */
    public static <T> String toJSONString(T object) {
        String jsonStr;
        try {
            jsonStr = mapper.writeValueAsString(object);
        } catch (Exception e) {
            LOGGER.error("Java Object Can't covert to JSON String!");
            throw new RuntimeException(e);
        }
        return jsonStr;
    }

    /**
     * 将 JSON 字符串转化为 Java 对象
     *
     * @param json
     * @param clazz
     * @param <T>
     * @return
     */
    public static <T> T toObject(String json, Class<T> clazz) {
        T object;
        try {
            object = mapper.readValue(json, clazz);
        } catch (Exception e) {
            LOGGER.error("JSON String Can't covert to Java Object!");
            throw new RuntimeException(e);
        }
        return object;
    }

}

UT如下:

/**
 * {@link JSONUtil} 测试用例
 * <p/>
 * Created by bysocket on 16/7/19.
 */
public class JSONUtilTest {

    @Test
    public void testToJSONString() {
        JSONObject jsonObject = new JSONObject(1, "bysocket", 33);
        String jsonStr = JSONUtil.toJSONString(jsonObject);
        Assert.assertEquals("{\"age\":1,\"name\":\"bysocket\",\"id\":33}", jsonStr);
    }

    @Test(expected = RuntimeException.class)
    public void testToJSONStringError() {
        JSONUtil.toJSONString(System.out);
    }

    @Test
    public void testToObject() {
        JSONObject jsonObject = new JSONObject(1, "bysocket", 33);
        String jsonStr = JSONUtil.toJSONString(jsonObject);
        JSONObject resultObject = JSONUtil.toObject(jsonStr, JSONObject.class);
        Assert.assertEquals(jsonObject.toString(), resultObject.toString());
    }

    @Test(expected = RuntimeException.class)
    public void testToObjectError() {
        JSONUtil.toObject("{int:1}", JSONObject.class);
    }
}

class JSONObject {
    int age;
    String name;
    Integer id;

    public JSONObject() {
    }

    public JSONObject(int age, String name, Integer id) {
        this.age = age;
        this.name = name;
        this.id = id;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    @Override
    public String toString() {
        return "JSONObject{" +
                "age=" + age +
                ", name='" + name + '\'' +
                ", id=" + id +
                '}';
    }
}

Run Console（抛出了异常信息）:

16/07/19 23:09:13 ERROR util.JSONUtil: JSON String Can't covert to Java Object!
16/07/19 23:09:13 ERROR util.JSONUtil: Java Object Can't covert to JSON String!

三、小结

相关对应代码分享在 Github 主页 请看到的Java小伙伴多交流多评论改进之。 参考 黄勇 smart

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