Article directory
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- 1. GsonUtils
- 2. String itself can add log information
- 3. Json and Map conversion
- 4. Convert Date to Json string
- 5. Json and List
conversion - 6. Compare the differences between two JSON strings
- 7. String filling: Filling in when generating document number
- 8. Use of String.format()
- 9. Truncate string
- 10.split
- The difference between isNotBlank and isNotEmpty
- 11. Determine whether the string is in Json string format
- 12. deep copy
- Supplement: About msyql’s Json format
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1. GsonUtils
- Json string to object
- Object to Json string
@UtilityClass
@Slf4j
public class GsonUtils {<!-- -->
private static final Gson GSON = new Gson();
public static String toJsonStr(Object object) {<!-- -->
return GSON.toJson(object);
}
public static String toJsonStr(Object obj, Type type) {<!-- -->
return GSON.toJson(obj, type);
}
public static <T> T fromJson(String json, Class<T> classOfT) {<!-- -->
return GSON.fromJson(json, classOfT);
}
public static <T> T fromJson(String json, Type typeOfT) {<!-- -->
return GSON.fromJson(json, typeOfT);
}
public static String toJson(Object object) {<!-- -->
try {<!-- -->
return GSON.toJson(object);
} catch (Exception e) {<!-- -->
log.error("Serialization failed", e);
}
return StringUtils.EMPTY;
}
}
- Tool usage
String str = "{"status":{"code":0,"__isset_bit_vector":[1]},"poiId":1}";
TResponse tResponseA = GsonUtils.fromJson(str, TResponse.class);
2. String itself can add log information
String.format("Duplicate asyncCreateTask request with requestId=%s, billNo=%s, finish it fast.", request.getRequestId(), request.getNo());
3. Json and Map conversion
map.put("0915", "1");
map.put("0916", "2");
String jsonStr = GsonUtils.toJsonStr(map);
Map<String,String> json2Map = GsonUtils.fromJson(jsonStr,new TypeToken<HashMap<String,String>>(){}.getType());
4. Convert Date to Json string
If there is a Date type attribute field in the class, you need to set the date format when creating gson.
Gson gson = new GsonBuilder()
.setDateFormat("yyyy-MM-dd")
.create();
System.out.println(gson.toJson(new Date()));
5. Json and List conversion
List<SkuDTO> list = GsonUtils.fromJson(jsonStr,new TypeToken<List<SkuDTO>>(){<!-- -->}.getType());
List<Long> list2 = GsonUtils.fromJson(Lists.newArrayList(1L,2L), new TypeToken<List<Long>>() {<!-- -->}.getType());
6. Compare the differences between two JSON strings
public void t() throws JSONException {<!-- -->
String s1 = "{"skuId":1,"skuName":"test","temp":2,"address":"bj"}";
String s2 = "{"skuId":1,"skuName":"test","temp":3,"author":"mjp"}";
// method one:
JSONCompareResult result = JSONCompare.compareJSON(s1, s2, JSONCompareMode.STRICT);
<dependency>
<groupId>org.skyscreamer</groupId>
<artifactId>jsonassert</artifactId>
<version>1.5.1</version>
<scope>test</scope>
</dependency>
// 1 out of 2, 2 out of 1
System.out.println(result.isMissingOnField());
List<FieldComparisonFailure> fieldMissing = result.getFieldMissing();
for (FieldComparisonFailure fieldComparisonFailure : fieldMissing) {<!-- -->
System.out.println(fieldComparisonFailure.getExpected());//address
}
// 1 out of 2, not 1 out of 2
System.out.println(result.isUnexpectedOnField());
List<FieldComparisonFailure> fieldUnexpected = result.getFieldUnexpected();
for (FieldComparisonFailure fieldComparisonFailure : fieldUnexpected) {<!-- -->
System.out.println(fieldComparisonFailure.getActual());//author
}
//There are both in 1 and 2, but the val value is different
System.out.println(result.isFailureOnField());
List<FieldComparisonFailure> list = result.getFieldFailures();
for (FieldComparisonFailure fieldComparisonFailure : list) {<!-- -->
System.out.println(fieldComparisonFailure.getField());//temp
System.out.println(fieldComparisonFailure.getActual());//3
System.out.println(fieldComparisonFailure.getExpected());//2
}
//Method 2:
HashMap<String, Object> diffMap = Maps.newHashMap();
Gson gson = new Gson();
Map<String,Object> json1Map = gson.fromJson(s1,new TypeToken<HashMap<String,Object>>(){<!-- -->}.getType());
Map<String,Object> json2Map = gson.fromJson(s2,new TypeToken<HashMap<String,Object>>(){<!-- -->}.getType());
for (Map.Entry<String, Object> entry : json1Map.entrySet()) {<!-- -->
String k1 = entry.getKey();
Object v1 = entry.getValue();
Object v2 = json2Map.get(k1);
// 1 out of 2, 2 out of 1
if (v2 == null) {<!-- -->
diffMap.put(k1, v1);
continue;
}
// Both 1 and 2 are present, but they are different
if (!Objects.equals(v1, v2)){<!-- -->
diffMap.put(k1, "expect:" + v1 + ", actual:" + v2);
}
}
json2Map.forEach((k2, v2) -> {<!-- -->
Object v1 = json1Map.get(k2);
// 1 out of 2, not 1 out of 2
if (v1 == null) {<!-- -->
diffMap.put(k2, v2);
}
});
System.out.println(diffMap);//{temp=expect:2.0, actual:3.0, address=bj, author=mjp}
}
7. String filling: filling when generating the document number
Long billType = 1L;
System.out.println("a" + StringUtils.leftPad(billType + "", 5, "0"));// a00001
That is, add 0 to the left side of billType until 00001 forms 5 digits.
The right padding and both side padding APIs are as follows:
public static String leftPad(final String str, final int size, String padStr)
public static String center(String str, final int size, String padStr)
8. Use of String.format()
Reference: https://blog.csdn.net/lonely_fireworks/article/details/7962171
- Simple to use
int time = 3;
String nameParis = String.format("The maximum number of times reached %s times", time);
- Complex use
String contentFormat = "The [%s] items you sold today are likely to be sold out, and the estimated sales loss is pcs [%s] pieces, and the estimated sales loss is [%s" + "] yuan, If you need to contact us for replenishment, please click "[Prompt Processing|%s]" to view details.";
String url = "sell.out.warning.link:https://xxx.xxx.xxx" + ".com?warnType=%s & amp;categoryId=%s"
String result = String.format(contentFormat, skuCount, salePcs.stripTrailingZeros().toPlainString(),
saleGmv.stripTrailingZeros().toPlainString(),
String.format(url, warnType, categoryId));
1. Fill warnTpe and categoryId into the url to become a complete connection url.
2. The sku number, pcs, GMV, and the four-digit value of the link url are processed in time and filled into %s of the contentFormat.
9. Truncate string
String s = "Hello to everyone is really good"; String truncate = StringUtils.truncate(s, 2, 4); System.out.println(truncate);//Good is true
10, split
https://www.runoob.com/java/java-string-split.html
The difference between isNotBlank and isNotEmpty
public static boolean isNotEmpty(String str): Determine whether a string is not empty. Space characters cannot be excluded here, that is, StringUtils.isNotEmpty(" ") = true
Here is an example:
StringUtils.isNotEmpty(null) = false
StringUtils.isNotEmpty("") = false
StringUtils.isNotEmpty(" ") = true
public static boolean isNotBlank(String str)
Determine whether a string is not empty, has a length that is not 0, and does not consist of whitespace characters, that is, StringUtils.isNotBlank(" ") = false
Here is an example:
StringUtils.isNotBlank(null) = false
StringUtils.isNotBlank("") = false
StringUtils.isNotBlank(" ") = false
Therefore, in some business scenarios, it is better to use isNotBlank than isNotEmpty.
11. Determine whether the string is in Json string format
try {<!-- -->
JsonElement parse = new JsonParser().parse(extra);
if (parse.isJsonObject() || parse.isJsonArray()) {<!-- -->
//YES
}
} catch (JsonSyntaxException e) {<!-- -->
//ignore
}
// NO
12. deep copy
// Object deep copy
MyUser myUser = new MyUser();
myUser.setSkuId(1L);
Gson gson = new Gson();
MyUser newUser = gson.fromJson(gson.toJson(myUser), MyUser.class);
System.out.println(newUser);
myUser.setSkuId(77777777777L);
System.out.println(newUser);
// Collection deep copy
List<MyUser> newList = JSON.parseArray(JSON.toJSONString(list), MyUser.class);//fastjson
System.out.println(newList);
u1.setSkuId(777777777777777L);
System.out.println(newList);
Supplement: About msyql’s Json format
Store the content in json format in mysql. The fields in mysql are json instead of Varchar.
- It is recommended to use field name json directly after 5.7
- Generally, varchar(n) is used. Note: n should not be too large. If it is too large, consider JSON.