从Java对象创建Avro字符串
我正在构建一个MapR ES Java producer,它通过JDBC连接到Oracle,并将结果集发布到流中 我想将填充的类对象序列化为Avro字符串,作为发布者的消息 我已经使用Maven Apache Avro插件为我的类对象生成了一个Avro字符串从Java对象创建Avro字符串,java,serialization,stream,avro,Java,Serialization,Stream,Avro,我正在构建一个MapR ES Java producer,它通过JDBC连接到Oracle,并将结果集发布到流中 我想将填充的类对象序列化为Avro字符串,作为发布者的消息 我已经使用Maven Apache Avro插件为我的类对象生成了一个Avro字符串 Schema Schema=ReflectionData.get().getSchema(MyClass.class) 但是,如果我有一个完全填充的MyClass对象,如何生成一个带有模式和填充数据的Avro字符串 我还没有找到这方面的好例
Schema Schema=ReflectionData.get().getSchema(MyClass.class)代码>
但是,如果我有一个完全填充的MyClass对象,如何生成一个带有模式和填充数据的Avro字符串
我还没有找到这方面的好例子。感谢您的帮助 假设我在java中反射了Customer类
import org.apache.avro.reflect.Nullable;
public class ReflectedCustomer {
private String firstName;
private String lastName;
@Nullable private String nickName;
// needed by the reflection
public ReflectedCustomer(){}
public ReflectedCustomer(String firstName, String lastName, String nickName) {
this.firstName = firstName;
this.lastName = lastName;
this.nickName = nickName;
}
public String getFirstName() {
return firstName;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
}
public String fullName(){
return this.firstName + " " + this.lastName + " " + this.nickName;
}
public String getNickName() {
return nickName;
}
public void setNickName(String nickName) {
this.nickName = nickName;
}
}
下面的代码将使用上面的ReflectedCustomer并生成Avro字符串,然后将其读回
import org.apache.avro.Schema;
import org.apache.avro.file.CodecFactory;
import org.apache.avro.file.DataFileReader;
import org.apache.avro.file.DataFileWriter;
import org.apache.avro.io.DatumReader;
import org.apache.avro.io.DatumWriter;
import org.apache.avro.reflect.ReflectData;
import org.apache.avro.reflect.ReflectDatumReader;
import org.apache.avro.reflect.ReflectDatumWriter;
import java.io.File;
import java.io.IOException;
public class ReflectionExamples {
public static void main(String[] args) {
// here we use reflection to determine the schema
Schema schema = ReflectData.get().getSchema(ReflectedCustomer.class);
System.out.println("schema = " + schema.toString(true));
// create a file of ReflectedCustomers
try {
System.out.println("Writing customer-reflected.avro");
File file = new File("customer-reflected.avro");
DatumWriter<ReflectedCustomer> writer = new ReflectDatumWriter<>(ReflectedCustomer.class);
DataFileWriter<ReflectedCustomer> out = new DataFileWriter<>(writer)
.setCodec(CodecFactory.deflateCodec(9))
.create(schema, file);
out.append(new ReflectedCustomer("Bill", "Clark", "The Rocket"));
out.close();
} catch (IOException e) {
e.printStackTrace();
}
// read from an avro into our Reflected class
// open a file of ReflectedCustomers
try {
System.out.println("Reading customer-reflected.avro");
File file = new File("customer-reflected.avro");
DatumReader<ReflectedCustomer> reader = new ReflectDatumReader<>(ReflectedCustomer.class);
DataFileReader<ReflectedCustomer> in = new DataFileReader<>(file, reader);
// read ReflectedCustomers from the file & print them as JSON
for (ReflectedCustomer reflectedCustomer : in) {
System.out.println(reflectedCustomer.fullName());
}
// close the input file
in.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
import org.apache.avro.Schema;
导入org.apache.avro.file.CodecFactory;
导入org.apache.avro.file.DataFileReader;
导入org.apache.avro.file.DataFileWriter;
导入org.apache.avro.io.DatumReader;
导入org.apache.avro.io.DatumWriter;
导入org.apache.avro.reflect.ReflectData;
导入org.apache.avro.reflect.ReflectDatumReader;
导入org.apache.avro.reflect.ReflectDatumWriter;
导入java.io.File;
导入java.io.IOException;
公共类ReflectionExamples{
公共静态void main(字符串[]args){
//这里我们使用反射来确定模式
Schema Schema=ReflectData.get().getSchema(ReflectedCustomer.class);
System.out.println(“schema=“+schema.toString(true));
//创建反射客户的文件
试一试{
System.out.println(“Writing customer reflected.avro”);
文件File=新文件(“customer reflected.avro”);
DatumWriter=新的ReflectDatumWriter(ReflectedCustomer.class);
DataFileWriter out=新的DataFileWriter(writer)
.setCodec(CodecFactory.deflateCodec(9))
.create(模式、文件);
追加(新的反射客户(“比尔”、“克拉克”、“火箭”);
out.close();
}捕获(IOE异常){
e、 printStackTrace();
}
//从avro读入我们的课堂
//打开反射客户的文件
试一试{
System.out.println(“Reading customer reflected.avro”);
文件File=新文件(“customer reflected.avro”);
DatumReader=新的ReflectDatumReader(ReflectedCustomer.class);
DataFileReader in=新的DataFileReader(文件,读取器);
//从文件中读取ReflectedCustomers并将其打印为JSON
for(ReflectedCustomer ReflectedCustomer:in){
System.out.println(reflectedCustomer.fullName());
}
//关闭输入文件
in.close();
}捕获(IOE异常){
e、 printStackTrace();
}
}
}