http断点续传简单实现（java)

/* f-nz{U  
**SiteFileFetch.java 1,5E`J  
*/ uytE^  
package NetFox; @(C1_  
import java.io.*; GElvz'S~  
import java.net.*; UU8pz{/  
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public class SiteFileFetch extends Thread { 7^T^($+6s&  
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SiteInfoBean siteInfoBean = null; //文件信息Bean WL{(Ob  
long[] nStartPos; //开始位置 h_d<!  
long[] nEndPos; //结束位置 /pp1~r.s?>  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 j1 =`|  
long nFileLength; //文件长度 cwV]!=RtO  
boolean bFirst = true; //是否第一次取文件 UJs$q\#RO  
boolean bStop = false; //停止标志  JMdPwI  
File tmpFile; //文件下载的临时信息 ?aW^+3i   
DataOutputStream output; //输出到文件的输出流 <LRey%{q  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） jjM{]  
public SiteFileFetch(SiteInfoBean bean) throws IOException aTBR|US  
{ {-BRt)L[  
siteInfoBean = bean; 1wW)tNKIF  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); {D g_?._d  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); HHjt/gc}`  
if(tmpFile.exists ()) l
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{ s}onsC  
bFirst = false; `<[6YH_  
read_nPos(); z6py"J@  
} /.M+fr S  
else <W]g2>9o9  
{ ];%0qb  
nStartPos = new long[bean.getNSplitter()]; KsrjdJx, '  
nEndPos = new long[bean.getNSplitter()]; ^*~;k|;&  
} %& _V0R\k  
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} ,7XtH>2s  
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public void run() >%E([:$A  
{ m0{!hF[^  
//获得文件长度 ) _ I,KEe  
//分割文件 #.[AK_S5&  
//实例FileSplitterFetch 8.bKb<y  
//启动FileSplitterFetch线程 P,=+W(s9}  
//等待子线程返回 q.2(OP>(  
try{ kF7V.m/~o  
if(bFirst) mJB2)^33a  
{  fI\
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nFileLength = getFileSize(); ^`f*'Z  
if(nFileLength == -1) %<8nF5  
{ !A1)|/a@  
System.err.println("File Length is not known!"); 6dAEM;$_Z  
} - y9>;6  
else if(nFileLength == -2) n}xhW'3hU=  
{ ?OdJqw0,G  
System.err.println("File is not access!"); >u%]6_[  
} PCnQ_A-Q  
else PM":Vd/  
{ )6~1 ^tD  
for(int i=0;i<nStartPos.length;i++) d3^OEwe  
{ rw
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nStartPos = (long)(i*(nFileLength/nStartPos.length)); v+"rZ  
} #}^-C&~  
for(int i=0;i<nEndPos.length-1;i++) 6mH/ m&  
{ 4x%(9_8{-  
nEndPos = nStartPos[i+1]; [#YE^[*qK  
} n]+W 3[i  
nEndPos[nEndPos.length-1] = nFileLength; 22(*J<  
} .lhn;*Yi  
} ^[Cv
26  
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v&FF|)$  
//启动子线程 w#i[_  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; ZDL']*)'  
for(int i=0;i<nStartPos.length;i++) U}Hwto`R  
{ x]5@>5  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), ]\RRqLDzkg  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), FZiW|G  
nStartPos,nEndPos,i); A|}l)!%  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); '2zL.:~  
fileSplitterFetch.start(); x( mE<UQN  
} *]JdHO  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), 7t9c7HLuj/  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); gqib:q;r  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", W\f9jfD  
nEndPos = " + nFileLength); avp;*G}  
// fileSplitterFetch[nPos.length-1].start(); dMx4ykrR  
ydv
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7nzGAz_W  
//等待子线程结束 M9!AIHq4  
//int count = 0; a:YI"*S  
//是否结束while循环 !2:3MbtR  
boolean breakWhile = false; iAMtejw  
6{d6s#|%  
5W =(+Q>C  
while(!bStop) ~{>?*Gd&T  
{ t"j|nz{m  
write_nPos(); B@Nt`ky0*  
Utility.sleep(500);
,~zj=F  
breakWhile = true; b=a!j=-D  
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for(int i=0;i<nStartPos.length;i++) 0%s|Zbo!>  
{ &$`hQgi  
if(!fileSplitterFetch.bDownOver) {+zJI-XN/  
{ *5$&`&,  
breakWhile = false; AgF5-tz6x  
break; +)nT|w45  
} iV.p5F
D  
} .'[/|4H  
if(breakWhile) M^rM-{?<  
break; >95TvJ  
Hg}I]!B  
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//count++; p<WFqLe(":  
//if(count>4) 7=4A;Ybq  
// siteStop(); VVWM9x  
} q&'Lbxc>c  
:<#`_K~'  
x2|6
  
System.err.println("文件下载结束！"); P4 ul[zZ  
} ,gnQa  
catch(Exception e){e.printStackTrace ();} LE?u`i,e=+  
} !a1i Un9  
[_y@M ]  
]6tkEyuq  
//获得文件长度 tqOi x/  
public long getFileSize() Ccfwax+  
{ ~!%0Z9>ap  
int nFileLength = -1; iZ[tHw||  
try{ k7_I$<YDj  
URL url = new URL(siteInfoBean.getSSiteURL()); V'Y
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HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); xFp<7p L  
httpConnection.setRequestProperty("User-Agent","NetFox"); +-068k(  
#`tD1T{;  
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int responseCode=httpConnection.getResponseCode();
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if(responseCode>=400) ?SY<~i<K-  
{ 71B3a  
processErrorCode(responseCode); YTY%#"  
return -2; //-2 represent access is error w#PZu+  
} ZofHic  
U2*6}c<  
+I|8Q|^SD  
String sHeader; eNySJf  
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& %}/AoU  
for(int i=1;;i++) %/0gWG  
{ 2]jPv0u  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); mp`PE=  
//Utility.log(in.readLine()); O{KB0"s>i  
sHeader=httpConnection.getHeaderFieldKey(i); <Mgf]v.QS  
if(sHeader!=null) ~] =?b)B  
{ ((3t:  
if(sHeader.equals("Content-Length")) t\5c@j p  
{ vW.%[]  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); %u]6KrG18b  
break; #t71U a  
} EHf)^]Z  
} sV0Z  
else #!!AbuhzK{  
break; >.dHt\  
} 993d/z|DX  
} Y4~vC[$x'  
catch(IOException e){e.printStackTrace ();} 3\!F\tqD \  
catch(Exception e){e.printStackTrace ();} \3NS>v[1  
I"!'AI-  
m% bE-#  
Utility.log(nFileLength); jOv"<  
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return nFileLength; `ENP=kL(+  
} ./maY1>T  
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//保存下载信息（文件指针位置） !y vJpdsof  
private void write_nPos() p?myuNd[  
{ 'tWAuI  
try{ o<4D=.g7D  
output = new DataOutputStream(new FileOutputStream(tmpFile)); y/4ny,s"  
output.writeInt(nStartPos.length); 'XfgBJF=  
for(int i=0;i<nStartPos.length;i++) Md9l+[@  
{ Fn,k!q  
// output.writeLong(nPos); vnsSy
33K  
output.writeLong(fileSplitterFetch.nStartPos); >iy^$bqF  
output.writeLong(fileSplitterFetch.nEndPos); >a]t<  
} ?R?Grw)`H  
output.close(); r=csi  
} A o
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catch(IOException e){e.printStackTrace ();} i>Iee^_(  
catch(Exception e){e.printStackTrace ();} gg8c7d:Q  
} GJak.,0t  
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//读取保存的下载信息（文件指针位置） F!CAitxd  
private void read_nPos() Dr'sIH^  
{ atnQC  
try{ ('WY5Yps  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); ,+-?Zv 2  
int nCount = input.readInt(); oeNzHp_  
nStartPos = new long[nCount]; aW`dFitpM  
nEndPos = new long[nCount]; a>b8-j=J  
for(int i=0;i<nStartPos.length;i++) [-VGArD[k,  
{ Qq0O0U  
nStartPos = input.readLong(); E/"SU*Co  
nEndPos = input.readLong(); ``-k{C#F  
} ;QidDi_s>  
input.close(); IxP^i{/1?  
} v' 0!=r  
catch(IOException e){e.printStackTrace ();} Iq,v  
catch(Exception e){e.printStackTrace ();} uYTCdZQh  
} #{>uC&
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private void processErrorCode(int nErrorCode) G^
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{ @^wpAQfd4  
System.err.println("Error Code : " + nErrorCode); 6F ;Or  
} ,I39&;Iq  
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*tG11gR,&  
//停止文件下载 0#=W#Jl>  
public void siteStop() %^')G+>i  
{ _?Ckq
 
bStop = true; Y`]rj-8f0B  
for(int i=0;i<nStartPos.length;i++) b]K>vhQV  
fileSplitterFetch.splitterStop(); k#jm7 +  
JjDS"hK#  
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} poY8
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} qL>v&Rd<  
//负责部分文件的抓取 \P@S"QO  
**FileSplitterFetch.java 28+HKbgK  
*/ @H4wHlb  
package NetFox; z`@z  
82.HH5Z{  
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import java.io.*; +I.v!P!^  
import java.net.*; FoLDMx(  
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public class FileSplitterFetch extends Thread { S| "TP\o  
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String sURL; //File URL GDmv0V$6  
long nStartPos; //File Snippet Start Position W+
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long nEndPos; //File Snippet End Position h.D^1  
int nThreadID; //Thread's ID 4L
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boolean bDownOver = false; //Downing is over i]@c.QiFN  
boolean bStop = false; //Stop identical U TS{H  
FileAccessI fileAccessI = null; //File Access interface wK
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException lR[z<2w\  
{ &&*wmnWCS{  
this.sURL = sURL; [[$Mh_MD  
this.nStartPos = nStart; Y)v
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this.nEndPos = nEnd; Hq-v@@0 *  
nThreadID = id; Uk|9@Auav  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 hvL6zCi  
} :^.u-bHI  
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public void run() _UaPwJ  
{ XJ _%!  
while(nStartPos < nEndPos && !bStop) sHF%=Vu  
{ '1lx{UzD  
) _#T c  
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try{ rSbQ}O4V  
URL url = new URL(sURL); >["Kd.ye  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); Y& m<lnB  
httpConnection.setRequestProperty("User-Agent","NetFox"); hN}5u"pS  
String sProperty = "bytes="+nStartPos+"-"; &#%D.@L  
httpConnection.setRequestProperty("RANGE",sProperty); x;*VCs
 
Utility.log(sProperty); lvG3<ls0K$  
. *Z#cq0  
![j(o!6&  
InputStream input = httpConnection.getInputStream(); |:}L<9Sq  
//logResponseHead(httpConnection); 0x6@{0  
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byte[] b = new byte[1024]; `}ZL'\G  
int nRead; |})rt5|f1!  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) ruWye1X;  
{ bf{Ep=-  
nStartPos += fileAccessI.write(b,0,nRead); VgUvD1v?}  
//if(nThreadID == 1) we @Yw6<  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); y.%i  
} 3k`NNA  
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% ghJ*iHR  
Utility.log("Thread " + nThreadID + " is over!"); td%Y4-+-  
bDownOver = true; A03I-^0g+  
//nPos = fileAccessI.write (b,0,nRead); ;Xz(B4N~o  
} aTi0bQW{  
catch(Exception e){e.printStackTrace ();}
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} <'VA=orD  
}  -\5[Nq{N  
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//打印回应的头信息 0VG^GKmx  
public void logResponseHead(HttpURLConnection con) &#$2;-q8+  
{ Xk;Uk
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for(int i=1;;i++) wX@H &)<s  
{ kK08W3@&t  
String header=con.getHeaderFieldKey(i); T$f:[ye]Z  
if(header!=null) zv&ePq\#  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); m<~>&mWr  
Utility.log(header+" : "+con.getHeaderField(header)); 9$8X>T^  
else $]xE$dzJ  
break; "Fo  
} 6_x}.bkIx=  
} 3{I=.mUUm  
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public void splitterStop() Q=dw 6  
{ oA5<[&~<  
bStop = true; -wJ  
} ccIDMJ=2
 
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} oD Q9.t  
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/* W` WLW8Qsw  
**FileAccess.java &E} 
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*//文件访问(定位，写) `8
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package NetFox; IY-(- a8  
import java.io.*; XL{{7%j  
nYmf(DV  
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public class FileAccessI implements Serializable{ 8') .ohD  
};4pZceV  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 ~5x4?2  
RandomAccessFile oSavedFile; ~NTDG  
long nPos; JS }_q1H  
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m T>b;  
public FileAccessI() throws IOException (jD'
+ "?  
{  zZS
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this("",0); J r=REa0  
} oHv{Y  
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public FileAccessI(String sName,long nPos) throws IOException r@N39O*Wq  
{ Q"x`+?!  
oSavedFile = new RandomAccessFile(sName,"rw"); L{+&z7M  
this.nPos = nPos; &ryl$!!3H  
oSavedFile.seek(nPos); .aVHd<M  
} 6{Krw\0  
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public synchronized int write(byte[] b,int nStart,int nLen) we6+2  
{ (CKhY~,/u  
int n = -1; Vu_7uSp,)  
try{ My'9S2Y8nv  
oSavedFile.write(b,nStart,nLen); ^K1~eb*K  
n = nLen; :HQ8M*o  
} +H2m<  
catch(IOException e) xMO[3D&D  
{ g] 7{5  
e.printStackTrace (); /y+;g{  
} lq78gOg{  
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return n; (:</R$I  
} Y3 Pz00x  
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} a+4`}:KA#  
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/* (1saof*p%  
**SiteInfoBean.java !;xf>API  
*/ ^?sSsHz  
package NetFox; VuJfo9 `E  
e>ZbZy?  
[="g|/M)  
public class SiteInfoBean { W07-JHV%  
AaCnTRG  
: 9djMsd  
private String sSiteURL; //Site's URL 02]8|B(E90  
private String sFilePath; //Saved File's Path Fyi?,,  
private String sFileName; //Saved File's Name y{&{=1#  
private int nSplitter; //Count of Splited Downloading File 5p#o1I
 
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public SiteInfoBean() ue^?/{OuT  
{//nSplitter的缺省值为5 42b=z//;  
//default value of nSplitter is 5 t?Njw7  
this("","","",5); *Dd(+NI  
} ]*k
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k=ior  
public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) X$j|/))  
{ MIk #60Ab  
sSiteURL= sURL; |)|vG_  
sFilePath = sPath; cAsSN.HFS  
sFileName = sName; S+Yy  
this.nSplitter = nSpiltter; &kr_CP:;  
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} ]XpU'/h>q;  
}R(0[0NQe-  
~]6Oz;~<3  
public String getSSiteURL() 0IT20.~  
{ fmZz
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return sSiteURL; Q9x` Uy  
} MZ|c7f&`  

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public void setSSiteURL(String value) ^,ZvKA"}+/  
{ ya*q;D  
sSiteURL = value; FzsS~C$wH{  
} K_<lO,[S  
Bcd0  
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public String getSFilePath() Gr"2G,,VI  
{ wFoR,oXtL/  
return sFilePath; U#FJ8CD&u  
} LzEE]i  
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>m;|I/2@  
public void setSFilePath(String value) HPd+Bd  
{ r,Y/4(.c7U  
sFilePath = value; BHRrXC\  
} 8YJqM,t5)  
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public String getSFileName() nHhD<a!  
{ RL]lt0O{  
return sFileName; .@/z-OgXg  
} HpjIp.  
=%nqMV(y  
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public void setSFileName(String value) %8`1Li6g  
{ d@q t%r3;  
sFileName = value; ui#1+p3G  
} 5>z:[OdY*  
lG[ )8!:+  
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public int getNSplitter() "#eNFCo7k  
{ W0uM?J\O  
return nSplitter; f'zFg["aZS  
} \PtC  

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public void setNSplitter(int nCount) @u'27c_<d3  
{ /iJcy:J  
nSplitter = nCount; ;Cp/2A}Xx  
} [2H(yLwO  
} *v7& T  
zf!\wY"`  
o"+&^  
/* WY.\<$7  
**Utility.java l.NkS  
*/ |2t7mat  
package NetFox; qeO6}A"^|  
%Cbc@=k  
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public class Utility { h+'eFAZ  
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public Utility() J/P@m_Yx  
{ +EB,7<5<  
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} ?PxYS%D_L  
O
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//线程睡眠 d=5}^v#4  
public static void sleep(int nSecond) WUOPYYW<o
 
{ $P}]|/Yb  
try{ F*jjcUk  
Thread.sleep(nSecond); p~zTRnm  
} a518N*]j  
catch(Exception e) uL
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{ Vwh&^{Eh  
e.printStackTrace (); qu~"C,  
} LXEu^F~{u#  
} 0 c'2rx  
s?\9i6  
//日志 fOjt` ~ToI  
public static void log(String sMsg) d\<aJOi+-  
{ #/sE{jm  
System.err.println(sMsg); 17[t_T&Ak9  
} M0IqQM57N  
X|n[9h:%  

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public static void log(int sMsg) [@?.}!  
{ RO3e  
System.err.println(sMsg); TboHP/  
} g#<?OFl  
} n YMf[kW  

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/* BMsy}08dQ  
**TestMethod.java wk <~Y 3u  
*/ LVcy.kU@]  
package NetFox; ppo$&W &z  
H=SMDj)s+  
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public class TestMethod { Pv$"DEXA2  
6g,3s?aT  
8{=(#]  
public TestMethod() 7/$Z7J!k  
{ ///xx/weblogic60b2_win.exe (a4y1k t-  
try{ J3}C T  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); ](6vG$\  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); @KRn3$U  
SiteFileFetch fileFetch = new SiteFileFetch(bean); g:6}zHK  
fileFetch.start(); ]
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} *z:lq2"G  
catch(Exception e){e.printStackTrace ();} MKYE]D;  
8\t7}8f  
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}  ~9jP++&  
gl{PLLe[}  
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public static void main(String[] args) P##(V!YR  
{ u2m{Y
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new TestMethod(); w I 7  
} ,7nb;$]  
} *E q7r>[  
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