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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