使用java编写一个flink，实时采集oracle的数据，然后输出到postgres

我明白了，您的要求是使用Java编写一个Flink程序，实时采集Oracle的数据，并将其输出到PostgreSQL。这个可以用Flink的JDBC Connector轻松完成。您需要先下载Flink的JDBC Connector依赖，然后在代码中使用OracleSourceFunction读取Oracle的数据，再使用PostgreSQLSinkFunction将数据写入PostgreSQL。您可以参考以下代码：

import org.apache.flink.api.common.functions.MapFunction;
import org.apache.flink.api.common.typeinfo.TypeInformation;
import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;
import org.apache.flink.streaming.api.functions.sink.SinkFunction;
import org.apache.flink.streaming.api.functions.source.SourceFunction;
import org.apache.flink.streaming.api.functions.source.TimestampedSourceFunction;
import org.apache.flink.streaming.connectors.jdbc.JdbcConnectionOptions;
import org.apache.flink.streaming.connectors.jdbc.JdbcSink;
import org.apache.flink.streaming.connectors.jdbc.JdbcStatementBuilder;
import org.apache.flink.streaming.connectors.jdbc.JdbcTableSink;
import org.apache.flink.streaming.connectors.jdbc.JdbcTableSource;
import org.apache.flink.streaming.connectors.jdbc.JdbcUpsertTableSink;
import org.apache.flink.streaming.connectors.jdbc.MySQLUpsertTableSink;
import org.apache.flink.streaming.connectors.jdbc.TableUtils;
import org.apache.flink.streaming.connectors.jdbc.internal.JdbcOutputFormat;
import org.apache.flink.streaming.connectors.kafka.FlinkKafkaConsumer;
import org.apache.flink.streaming.util.serialization.SimpleStringSchema;
import org.apache.flink.types.Row;
import org.apache.flink.util.StringUtils;

import java.sql.PreparedStatement;
import java.sql.SQLException;
import java.sql.Timestamp;
import java.util.Optional;
import java.util.Properties;

public class OracleToFlinkToPostgreSQLDemo {
    public static void main(String[] args) throws Exception {
        final StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();
        env.enableCheckpointing(60000);

        // read Oracle data
        SourceFunction<Row> oracleSource = new OracleSourceFunction("jdbc:oracle:thin:@ip:port:sid","user","password","SELECT * FROM source_table");
//        TimestampedSourceFunction<Row> timestampedSource = new OracleSourceFunction("jdbc:oracle:thin:@ip:port:sid","user","password","SELECT event_time, field1, field2 FROM source_table")
//                .assignTimestampsAndWatermarks(r -> new Timestamp(r.getTimestamp("event_time").getTime()));
//        env.addSource(timestampedSource)
        env.addSource(oracleSource)
                // transform data
                .map(new MapFunction<Row, String>() {
                    @Override
                    public String map(Row value) throws Exception {
                        return value.toString();
                    }
                })
                // write PostgreSQL data
                .addSink(new PostgresSinkFunction("jdbc:postgresql://ip:port/database","user","password","target_table"));

        env.execute("OracleToFlinkToPostgreSQL Demo");
    }

    private static class OracleSourceFunction extends JdbcTableSource {

        public OracleSourceFunction(String url, String user, String password, String query) throws SQLException {
            super(JdbcConnectionOptions.builder()
                    .withUrl(url)
                    .withUsername(user)
                    .withPassword(password)
                    .build(),
                    Optional.empty(),
                    query,
                    TypeInformation.of(Row.class));
        }

        @Override
        public String getTableName() {
            return "source_table";
        }
    }

    private static class PostgresSinkFunction implements SinkFunction<String> {
        private final String url;
        private final String user;
        private final String password;
        private final String query;

        public PostgresSinkFunction(String url, String user, String password, String table) {
            this.url = url;
            this.user = user;
            this.password = password;
            this.query = TableUtils.getUpsertStatement(table,
                    new String[]{"field1", "field2"},
                    new String[]{"?","?"});
        }

        @Override
        public void invoke(String value) throws Exception {
            try (JdbcOutputFormat outputFormat = JdbcOutputFormat.buildJdbcOutputFormat()
                    .setDrivername("org.postgresql.Driver")
                    .setDBUrl(url)
                    .setUsername(user)
                    .setPassword(password)
                    .setQuery(query)
                    .finish()) {
                outputFormat.writeRecord(Row.of(value.split(",",2))); // 需要把逗号分割的值转成两个字段
            }
        }
    }
}

此代码演示了如何使用JDBC Connector读取Oracle表中的数据，并将其写入PostgreSQL中的另一个表中。在代码中，您需要将URL、用户名、密码、查询和目标表的名称替换为实际的值。此外，您还需要将MySQL替换为PostgreSQL驱动程序。