要好好了解java 8里的 Predicate，Function,Consumer这几个类，跟lambda有关。
stream to List
List<Person> filtered =
persons
.stream()
.filter(p -> p.name.startsWith("P"))
.collect(Collectors.toList());运行： /usr/libexec/java_home
有了缺省方法的interface与abstract class有什么区别？？
Supplier这个东西是干什么的？
NIO 这篇文章讲得最好： https://www.ibm.com/developerworks/cn/education/java/j-nio/j-nio.html
JDK1.5_update10版本使用epoll替代了传统的select/poll，极大的提升了NIO通信的性能。
Spring boot是可以写web的，请看：https://stormpath.com/blog/build-spring-boot-spring-security-app
Spring的BOM Maven "Bill Of Materials" Dependency
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-framework-bom</artifactId>
<version>5.0.0.M3</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>加了这个依赖后，会强制保证spring的所有的spring dependencies are at the version. and you no long need to verify the <version> attribute when depending on Spring Framework artifacts.
<dependencies>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context</artifactId>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-web</artifactId>
</dependency>
<dependencies>Spring的配置已经可以不用xml了，现在大家都用Java-Based configuration. @Configuration ,@Bean ,@Import,@DependOn annotations.
我们引用Spring时会看到很多版本,snapshot结尾的，M结尾的，GA的，一定要用GA的，不要追求新版本。
Spring Framework 4.0 is now focused primarily on Servlet 3.0+ environments. If you are using the Spring MVC Test Framework you will need to ensure that a Servlet 3.0 compatible JAR is in your test classpath.
引入spring-websocket 可以实现websocket了。
新的SocketUtils enables you scan for free TCP and UDP server ports on localhost.
org.springframework.mock.web 现在 now based on Servlet 3.0 API.
The interface org.springframework.context.ApplicationContext represents the Spring IoC container.
bean可以设置别名。
<alias name="fromName" alias="toName"/>@RestController 可以直接让Controller输出json
搞定spring boot与alibaba dubbo的整合！昨天的问题找到了，是因dubbo依赖了spring 2.5.6,把它从pom里exclusions就可以了。
Change the embedded tomcat http port. http://docs.spring.io/spring-boot/docs/current/reference/htmlsingle/#howto-change-the-http-port
在做Spring boot的junit test时报错：
java.lang.IllegalArgumentException: URI is not absolute
测试代码是这样的：
/**
* Created by harley on 12/22/16.
*/
@RunWith(SpringJUnit4ClassRunner.class)
@SpringApplicationConfiguration(classes = OpenApiGateway.class)
@WebIntegrationTest({"server.port=0", "management.port=0"})
public class RequestValidationTest {
RestTemplate template = new TestRestTemplate();
@Test
public void testRequest() {
String body = this.template.getForObject("/instances", String.class);
System.out.println(body);
}
}"/instances"肯定不是个绝对地址啊,而且端口是随机的，所以也无法拼出一个完整的URI。
通过下面的blog，知道了如何注入端口号。 https://blog.jayway.com/2014/07/04/integration-testing-a-spring-boot-application/
修改后的代码如下：
/**
*
*/
@RunWith(SpringJUnit4ClassRunner.class)
@SpringApplicationConfiguration(classes = OpenApiGateway.class)
@WebIntegrationTest({"server.port=0", "management.port=0"})
public class RequestValidationTest {
RestTemplate template = new TestRestTemplate();
@Value("${local.server.port}")
private int port;
@Test
public void testRequest() {
String body = this.template.getForObject("http://127.0.0.1:" + port +"/instances", String.class);
System.out.println(body);
}
}JPA Many to one mapping. https://hellokoding.com/jpa-one-to-many-relationship-mapping-example-with-spring-boot-maven-and-mysql/
http://stackoverflow.com/a/22307705
生产环境与开发环境的配置经常是不同的，但是打包成Fat Jar时，我们如何修改配置呢？
根据spring boot reference，是可以把配置外部化的。
java -Dspring.config.location=/target/application.properties -jar target/myproject-0.0.1-SNAPSHOT.jar
$ mvn archetype:generate -DgroupId=com.chinaops -DartifactId=CloudOps -DarchetypeArtifactId=maven-archetype-gwt
$ mvn archetype:generate -DgroupId=com.vianet -DartifactId=ManrecaServer -DarchetypeArtifactId=maven-archetype-quickstart
$ mvn archetype:generate -DgroupId=com.chinaops.tuts -DartifactId=Tuts -DarchetypeArtifactId=maven-archetype-webapp
$ mvn archetype:create -DarchetypeGroupId=com.totsp.gwt \
-DarchetypeArtifactId=maven-googlewebtoolkit2-archetype \
-DarchetypeVersion=1.0.4 \
-DremoteRepositories=http://gwt-maven.googlecode.com/svn/trunk/mavenrepo \
-DgroupId=com.chinaops \
-DartifactId=CloudOps
mvn install:install-file \
-Dfile=/Users/harley/Downloads/typica-m4c-1.6.jar \
-DgroupId=china-ops \
-DartifactId=ecloud-typica \
-Dversion=1.6 \
-Dpackaging=jar \
-DgeneratePom=true
# Print dependency tree.
mvn dependency:tree如果mvn archetype:generate卡住了，增加参数-DarchetypeCatalog=internal后解决卡住问题。
$ mvn -X archetype:generate -DgroupId=cn.com.xiangcloud -DartifactId=xiangcloud-common -DarchetypeArtifactId=maven-archetype-quickstart -DarchetypeCatalog=internal
如果出现问题，请加-X用来调试。
https://maven.apache.org/guides/mini/guide-creating-archetypes.html
mvn archetype:create-from-project -Darchetype.filteredExtensions=java
cd target/generated-sources/archetype/
mvn install
mvn archetype:generate -DarchetypeCatalog=local
我最近在整合tsf和seata，发现一个奇怪的现象，可能是好久没有做java的开发了，发现一个类死活编译不成功，明明依赖已经加上了，就是编译不成功。后来在左侧的outline tree里我发现我引用的jar包无法展开，也就是无法查看其内容，于是我在Finder里打开一看，是0字节的jar，我晕。Maven在下载jar包时，是同时下载了checksum的文件的。难道不应该校验一下，如果这种包就提示失败吗？
后来我发现maven有一个命令行的选项 -C, --strict-checksums就是用来做这个的。加入这个选项后，如果jar没有通过校验，build会直接出错。
Nexus里的repo有hosts、proxy、group三种，
hosts就是host在Nexus里的repo，当你运行mvn deploy时，artifact 就会Push到这个repo.
proxy类型
A proxy repository is a repository that is linked to a remote repository. Any request for a component is verified against the local content of the proxy repository. If no local component is found, the request is forwarded to the remote repository. The component is then retrieved and stored locally in the repository manager, which acts as a cache. Any future requests for the same component are fulfilled from the local storage, eliminating network bandwidth and time overhead when retrieving the component from the remote repository again
Group类型
A repository group is a collection of other repositories, where you can combine multiple repositories of the same format into a single item. This represents a powerful feature of Nexus Repository Manager that lets developers rely on a single URL for their configuration needs. For example, if your group has a Maven Central proxy repository and a hosted repository for 3rd party JARs, these can be combined into a group with one URL for builds.
最流行的：VisualVM
次流行的：No profiler
模拟 最流行的：Mockito
最受欢迎的Java模拟测试框架。
自动化Web浏览测试
最流行的：Selenium
Selenium只是自动化浏览测试。开发者经常使用这个工具配合其他的测试框架，来测试大型Web应用。
GraalVM: 可以把java的代码编码成本地代码，这个有点厉害了。
https://medium.com/graalvm/instant-netty-startup-using-graalvm-native-image-generation-ed6f14ff7692
GraalVM native image实现的原理是用 Substrate VM 来编译java,这个vm会被打包进native的二进制可执行文件里。由它来负责内存的相关的管理。
这个pdf讲了它的https://www.oracle.com/technetwork/java/jvmls2015-wimmer-2637907.pdf
Substrate VM is …
an embeddable VM
for, and written in, a subset of Java
optimized to execute Truffle languages
ahead-of-time compiled using Graal
integrating with native development tools.
Drool是java的规则引擎。
[A look at Java 7's new features] (http://radar.oreilly.com/2011/09/java7-features.html)
10 JDK 7 Features to Revisit, Before You Welcome Java 8
java 7的 可以自动关闭资源了: The try-with-resources Statement
这个非常好，而且作者一直在更新：Java 8 Features – The ULTIMATE Guide
What's New in Java 8 https://leanpub.com/whatsnewinjava8/read#leanpub-auto-optional 这个讲得真不错,尤其是streaming部分讲得挺详细的。
What’s New in Java 8: Lambdas 这个作者的其它文章也很好。
Joda-Time 在java 8之前是java 8之前事实上的data time标准库？（靠，我居然没用过）。Java 8的New Date Time API受其严重启发而生。
得到系统的Zone
System.out.println(ZoneId.systemDefault().toString());
System.out.println("ldt " + LocalDateTime.now().atZone(ZoneId.systemDefault()).toInstant().toEpochMilli());
//LocalDateTime to ISO 8601
DateTimeFormatter formatter = DateTimeFormatter.ISO_INSTANT;
System.out.println(formatter.format(LocalDateTime.now().atZone(ZoneId.systemDefault()).toInstant()));
//Parse ISO 8601
ZonedDateTime zonedDateTime = ZonedDateTime.parse("2013-08-27T14:30:10Z");
System.out.println(zonedDateTime.toString());
System.out.println(zonedDateTime.toInstant().getEpochSecond());
System.out.println(zonedDateTime.toInstant().toEpochMilli());
//Convert java.util.Date to LocalDateTime
Date in = new Date();
LocalDateTime ldt = LocalDateTime.ofInstant(in.toInstant(), ZoneId.systemDefault());
Date out = Date.from(ldt.atZone(ZoneId.systemDefault()).toInstant());
//当前时间加一个月
LocalDateTime superBowlXLV = LocalDateTime.of(2011, Month.FEBRUARY, 6,
0, 0);
LocalDateTime sippinFruityDrinksInMexico = superBowlXLV.plusMonths(1);要看看这个包java.util.function
Method References ，只要是参数类型一样，返回结果兼容，就可以用。方法名可以不一样，有点像函数指针。但是对constructor的引用有点不一样。
可以用JPA Tools来生成 entity class. 用eclipse. http://shengwangi.blogspot.com/2014/12/how-to-create-java-classes-from-tables.html
The Java Persistence Query Language http://docs.oracle.com/javaee/6/tutorial/doc/bnbtg.html
https://dzone.com/articles/all-jpa-annotations-mapping-annotations
Liquibase Rails的Db Migration的java alternative.
开发过程中，可以使用命令行来migrate，生产环境用servlet listener的来自动运行，这样的缺点是每次启动时都要运行这个，如果不小心修改了changelog文件，可能会有风险。
这个框架实在比Play web framework还要好，有点像django了。而且还是redhat的开发的。喜欢呀。。。 这绝对是我以后开发java web应用首选的web framework了。
System properties can be handed to the application through the -D flag during startup. The following examples assign the value youshallnotpass to the attribute quarkus.datasource.password.
-
For Quarkus dev mode:
./mvnw quarkus:dev -Dquarkus.datasource.password=youshallnotpass -
For a runner jar:
java -Dquarkus.datasource.password=youshallnotpass -jar target/quarkus-app/quarkus-run.jar -
For a native executable:
./target/myapp-runner -Dquarkus.datasource.password=youshallnotpass
quarkus.hibernate-orm.database.generation
这个配置决定在每次启动时对数据库的操作，如果配置为drop-and-create那么在启动时会把所有的表都drop掉，然后重新创建，这个配置在开发环境还可以，如果是生产环境，不要这样配置。
quarkus.hibernate-orm."persistence-unit-name".database.generation
Select whether the database schema is generated or not. drop-and-create is awesome in development mode. This defaults to 'none', however if Dev Services is in use and no other extensions that manage the schema are present this will default to 'drop-and-create'. Accepted values: none, create, drop-and-create, drop, update, validate.
Environment variable: QUARKUS_HIBERNATE_ORM_DATABASE_GENERATION
By default, Quarkus provides three profiles, that activate automatically in certain conditions:
- dev - Activated when in development mode (i.e.
quarkus:dev) - test - Activated when running tests
- prod - The default profile when not running in development or test mode 默认是生产环境
-
For a runner jar:
export QUARKUS_DATASOURCE_PASSWORD=youshallnotpass ; java -jar target/quarkus-app/quarkus-run.jar -
For a native executable:
export QUARKUS_DATASOURCE_PASSWORD=youshallnotpass ; ./target/myapp-runner
Environment variables names follow the conversion rules specified by MicroProfile Config. Config searches three environment variables for a given property name (e.g. foo.BAR.baz):
-
foo.BAR.baz- Exact match -
foo_BAR_baz- Replace each character that is neither alphanumeric nor_with_ -
FOO_BAR_BAZ- Replace each character that is neither alphanumeric nor_with_; then convert the name to upper case
SmallRye Config specifies additional conversion rules.
-
A property with double quotes
foo."bar".baz, replace each character that is neither alphanumeric nor_with_:FOO__BAR__BAZ -
A property with dashes
foo.bar-baz, replace each character that is neither alphanumeric nor_with_:FOO_BAR_BAZ -
An indexed property
foo.bar[0]orfoo.bar[0].baz, replace each character that is neither alphanumeric nor_with_:FOO_BAR_0_orFOO_BAR_0__BAZ
In some situations, looking up the exact property name is impossible. This is the case for configuration names that contain user defined path segments.
Applying the conversion rules for Environment Variables names, quarkus.datasource."datasource-name".jdbc.url becomes QUARKUS_DATASOURCE__DATASOURCE_NAME__JDBC_URL. The configuration will work as expected if both properties are available in the Config system.
If only QUARKUS_DATASOURCE__DATASOURCE_NAME__JDBC_URL is present, the Config system needs to reconvert the configuration name to its most likely dotted format. This works fine for fixed configuration segments, but not for names that contain dynamic segments. In this case, Quarkus is unable to determine if DATASOURCE_NAME should be converted to datasource.name or datasource-name (or any other special character separator).
For this reason, such properties always require their dotted version name in another source (the value can be left empty) to disambiguate the Environment Variable name. It will provide additional information to perform a two-way conversion and match the property names together.
# value can be left empty quarkus.datasource."datasource-name".jdbc.url=
EXPORT QUARKUS_DATASOURCE__DATASOURCE_NAME__JDBC_URL=jdbc:postgresql://localhost:5432/database
Play居然可以实现hot reload而且不需要任何外部工具， 这才是我想要的呀！虽然只能是stateless的
Play, Anatomy of a web framework: Hot redeploy.
it's only possible because Play is stateless,
Freemarker template inheritance - Implementation Specific
如何live reload log4j configuration. http://stackoverflow.com/a/4599083
判断http返回值是2xx。
this.mvc.perform(post("/api/cliente/pessoafisica/post")
.contentType(MediaType.APPLICATION_JSON)
.content("teste"))
.andDo(print())
.andExpect(status().is2xxSuccessful());获取response里的json里的某个字段。
mockMvc.perform(get("/springmvc/api/getUser/{id}", userId))
.andDo(print())
.andExpect(status().isOk())
.andExpect(jsonPath("id").value(userId))
.andExpect(jsonPath("name").value(userName))
.andExpect(jsonPath("password").value(userPassword));有时候我们需要把我们Mock的Service注入到我们要测试的controller里去，下面的链接讲了如何去做这件事。
@Spy 用来标识那些不mock的属性，比如我们的controller里有一个OrderManager和ProductManager,我们在测试时希望ProductManager用mock的，但是OrderManager我们希望仍然是@Autowired.那我们在测试类里就要把它加上@Spy这个annotation.
package com.ibm.cloud.fawvw.demo;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.ibm.cloud.fawvw.demo.controller.OrderController;
import com.ibm.cloud.fawvw.demo.manager.OrderManager;
import com.ibm.cloud.fawvw.demo.model.Order;
import com.ibm.cloud.fawvw.demo.model.Product;
import com.ibm.cloud.fawvw.demo.service.ProductService;
import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.mockito.InjectMocks;
import org.mockito.Mock;
import org.mockito.MockitoAnnotations;
import org.mockito.Spy;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.web.servlet.AutoConfigureMockMvc;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
import org.springframework.test.web.servlet.MockMvc;
import org.springframework.test.web.servlet.setup.MockMvcBuilders;
import java.util.Date;
import static org.mockito.Mockito.when;
import static org.springframework.http.MediaType.APPLICATION_JSON;
import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.post;
import static org.springframework.test.web.servlet.result.MockMvcResultHandlers.print;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.jsonPath;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;
//import org.springframework.test.context.junit4.SpringRunner;
@RunWith(SpringJUnit4ClassRunner.class)
@SpringBootTest
@AutoConfigureMockMvc
public class OrderTest {
@Autowired
private MockMvc mvc;
@InjectMocks
OrderController controllerUnderTest;
@Autowired
private ObjectMapper objectMapper;
@Mock
ProductService productService;
@Spy
@Autowired
private OrderManager orderManager;
@Test
public void testPlaceOrder() throws Exception {
// ProductService productService = mock(ProductService.class);
Product product = new Product();
product.setId(1);
product.setName("Apple magic mouse");
product.setPrice(348.00f);
when(productService.getProductById(1)).thenReturn(product);
Order order = new Order();
order.setProductId(1);
order.setQuantity(2);
order.setUserId(1);
order.setCreatedAt(new Date());
this.mvc.perform(post("/orders", order)
.contentType(APPLICATION_JSON)
.content(objectMapper.writeValueAsString(order))
).andExpect(status().isOk());
// .andExpect(content().string("Hello World"));
this.mvc.perform(get("/orders/get/{id}", 8))
.andDo(print())
.andExpect(status().isOk())
.andExpect(jsonPath("id").value(8))
.andExpect(jsonPath("quantity").value(2));
}
@Before
public void setup() {
MockitoAnnotations.initMocks(this);
this.mvc = MockMvcBuilders.standaloneSetup(controllerUnderTest).build();
}
}如何从MVCMock的jsonPath里返回某个属性的值?
How to retrieve String from jsonPath in mvcMock?
https://stackoverflow.com/a/49537158
没有二十年功力，写不出Thread.sleep(0)这一行“看似无用”的代码！
http://www.infoq.com/cn/articles/netty-high-performance 这里面讲了Reactor主从多线程模型，非常好。
I installed two Java vm on my mac ,one is oracle java 1.8 and the other is dcevm. Today I download the newest eclipse , but i can not startup with error "Failed to create java virtual machine". I googled and try all solution , no help. I specified the dcevm in eclipse.ini it failed too. Then I changed jvm to oracle jvm , It started up !
eclipse 换行插件
http://dev.cdhq.de/eclipse/word-wrap/
JRebel or Spring Loaded
Thymeleaf
Liquibase 类似于Rails Migration的东西。请见下面的具体章节。
Jtwig 这个模板系统很强，而且能在Spring里使用。推荐。
Hotswap Agent project : http://hotswapagent.org/ 这个是用DCEVM的，实现的是jvm级的reload，比Spring loaded更强。
我现在用的就是Hotswap Agent 的JDK。
Dynamic Source Lookup plugin for Eclipse : https://github.com/ifedorenko/com.ifedorenko.m2e.sourcelookup
Wiremock 用来mock一些api，主要用来测试。
阿里的RPC框架 dubbo
https://yq.aliyun.com/articles/60789
IDEA spring boot & spring Loaded
首先要设计项目自动编译
设置里：
Build > Compiler > Build project automatically.
然后在启动参数里添加
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<configuration>
<jvmArguments>
-javaagent:/Users/harley/.m2/repository/org/springframework/springloaded/1.2.6.RELEASE/springloaded-1.2.6.RELEASE.jar -noverify
</jvmArguments>
</configuration>
<executions>
<execution>
<goals>
<goal>repackage</goal>
</goals>
</execution>
</executions>
</plugin>