1. 复杂JSON字符串转模型
1 import com.fasterxml.jackson.core.type.TypeReference; 2 import com.fasterxml.jackson.databind.ObjectMapper;
1 ObjectMapper mapper = new ObjectMapper(); 2 List<CustomModel> list = mapper.readValue(json, new TypeReference<List<CustomModel>>() { });
2. 在非Bean对象调用Spring Bean管理的对象
1 package com.wunaozai.demo 2 3 import org.springframework.beans.BeansException; 4 import org.springframework.context.ApplicationContext; 5 import org.springframework.context.ApplicationContextAware; 6 import org.springframework.stereotype.Component; 7 8 /** 9 * 为不是spring所管理的对象,需要引用spring管理对象的时候所用的工具类 10 * @author wunaozai 11 * 12 */ 13 @Component 14 public class SpringApplicationContext implements ApplicationContextAware { 15 16 protected static ApplicationContext context; 17 18 @Override 19 public void setApplicationContext(ApplicationContext ctx) throws BeansException { 20 context = (ApplicationContext) ctx; 21 } 22 23 public static ApplicationContext getContext(){ 24 return context; 25 } 26 27 }
调用
1 CustomerService influxdbconnectService = SpringApplicationContext.getContext().getBean(CustomerService.class);
3. Spring Boot 项目出现 pom.xml 第一行莫名的错误，在pom.xml 的 properties段下增加
1 <maven-jar-plugin.version>3.0.0</maven-jar-plugin.version>
4. eclipse maven 更换 阿里源， 需要配置 settings.xml 文件
1 <?xml version="1.0" encoding="UTF-8"?> 2 <settings> 3 <mirrors> 4 <mirror> 5 <id>alimaven</id> 6 <name>aliyun maven</name> 7 <url>http://maven.aliyun.com/nexus/content/groups/public/</url> 8 <mirrorOf>central</mirrorOf> 9 </mirror> 10 </mirrors> 11 <profiles> 12 <profile> 13 <id>nexus</id> 14 <repositories> 15 <repository> 16 <id>nexus</id> 17 <name>local private nexus</name> 18 <url>http://maven.oschina.net/content/groups/public/</url> 19 <releases> 20 <enabled>true</enabled> 21 </releases> 22 <snapshots> 23 <enabled>false</enabled> 24 </snapshots> 25 </repository> 26 </repositories> 27 28 <pluginRepositories> 29 <pluginRepository> 30 <id>nexus</id> 31 <name>local private nexus</name> 32 <url>http://maven.oschina.net/content/groups/public/</url> 33 <releases> 34 <enabled>true</enabled> 35 </releases> 36 <snapshots> 37 <enabled>false</enabled> 38 </snapshots> 39 </pluginRepository> 40 </pluginRepositories> 41 </profile></profiles> 42 </settings>
5. spring boot 项目，用maven编译打包时，使用wrapper时遇到下载apache-maven失败，可以到 .m2/wrapper/dists/apache-maven-** 目录下，将离线包放到该目录下。或者修改wrapper目录下的maven-wrapper.properties文件里面的distributionUrl 为本地离线地址，都是可以的。
6. mybatis-plus 打印SQL详细日志，在application配置文件中增加
1 #mybatis-plus 2 mybatis-plus.mapper-locations=classpath:com/wunaozai/demo/mapper/*.xml 3 mybatis-plus.configuration.log-impl=org.apache.ibatis.logging.stdout.StdOutImpl
7. springboot中默认使用jackson做json序列化和反序列化，后台接收数据时将上述日期字符串转成LocalDateTime时，会报如下错误
JSON parse error: Cannot deserialize value of type java.time.LocalDateTime from String “2018-09-20 08:01:00”: Failed to deserialize java.time.LocalDateTime: (java.time.format.DateTimeParseException) Text ‘2018-09-20 08:01:00’ could not be parsed at index 10; nested exception is com.fasterxml.jackson.databind.exc.InvalidFormatException: Cannot deserialize value of type java.time.LocalDateTime from String “2018-09-20 08:01:00”: Failed to deserialize java.time.LocalDateTime: (java.time.format.DateTimeParseException) Text ‘2018-09-20 08:01:00’ could not be parsed at index 10
解决办法：
导入jackson-datatype
1 <dependency> 2 <groupId>com.fasterxml.jackson.datatype</groupId> 3 <artifactId>jackson-datatype-jsr310</artifactId> 4 </dependency>
配置bean
1 @Bean 2 public ObjectMapper serializingObjectMapper() { 3 JavaTimeModule module = new JavaTimeModule(); 4 LocalDateTimeDeserializer deserializer = 5 new LocalDateTimeDeserializer(DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss")); 6 module.addDeserializer(LocalDateTime.class, deserializer); 7 ObjectMapper object = Jackson2ObjectMapperBuilder.json() 8 .modules(module) 9 .featuresToDisable(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS) 10 .build(); 11 return object; 12 }
8. PCM 转 WAV 格式
PcmToWav.java
1 package com.wunaozai.demo.pcm2wav; 2 3 import java.io.FileInputStream; 4 import java.io.FileOutputStream; 5 import java.io.IOException; 6 7 /** 8 * PCM 转 WAV 9 * @author wunaozai 10 * @Date 2020-11-03 11 */ 12 public class PcmToWav { 13 public static void main(String[] args) throws Exception { 14 convertAudioFiles("F:\\voice\\1311458187862568961.pcm", "F:\\voice\\1311458187862568961.pcm.mp3"); 15 } 16 17 public static void convertAudioFiles(String src, String dest) throws IOException { 18 FileInputStream fis = new FileInputStream(src); 19 FileOutputStream fos = new FileOutputStream(dest); 20 //计算长度 21 byte[] buf = new byte[1024 * 4]; 22 int size = fis.read(buf); 23 int PCMSize = 0; 24 while (size != -1) { 25 PCMSize += size; 26 size = fis.read(buf); 27 } 28 fis.close(); 29 30 //填入参数，比特率等等。这里用的是16位单声道 8000 hz 31 WaveHeader header = new WaveHeader(); 32 //长度字段 = 内容的大小（PCMSize) + 头部字段的大小(不包括前面4字节的标识符RIFF以及fileLength本身的4字节) 33 header.fileLength = PCMSize + (44 - 8); 34 header.FmtHdrLeth = 16; 35 header.BitsPerSample = 16; 36 header.Channels = 1; 37 header.FormatTag = 0x0001; 38 header.SamplesPerSec = 16000; 39 header.BlockAlign = (short) (header.Channels * header.BitsPerSample / 8); 40 header.AvgBytesPerSec = header.BlockAlign * header.SamplesPerSec; 41 header.DataHdrLeth = PCMSize; 42 43 byte[] h = header.getHeader(); 44 45 assert h.length == 44; //WAV标准，头部应该是44字节 46 // write header 47 fos.write(h, 0, h.length); 48 // write data stream 49 fis = new FileInputStream(src); 50 size = fis.read(buf); 51 while (size != -1) { 52 fos.write(buf, 0, size); 53 size = fis.read(buf); 54 } 55 fis.close(); 56 fos.close(); 57 System.out.println("Convert OK!"); 58 } 59 }